Question 1
(a) A student investigates the conditions that affect the germination of seeds. Each test-tube has different conditions, as shown in Fig. 1.1. (Sub-topic: B15.3)
Table 1.1 summarises these conditions.
Only the seeds in test-tube A germinate.
(i) State one conclusion about the conditions needed for germination shown by test-tubes:
A and B ……….
A and C ……….
▶️Answer/Explanation
Answer:
A and B: Warmth / suitable temperature is required for germination.
A and C: Moisture / water is required for germination.
(ii) Suggest why the seeds in test-tube D did not germinate. (Sub-topic: B15.3)
▶️Answer/Explanation
Answer:
The seeds in test-tube D did not germinate because there was no oxygen available.
(iii) Ten cress seeds were used in test-tube A. Only eight seeds germinated.
Calculate the percentage of seeds that germinated. (Sub-topic: B15.3)
▶️Answer/Explanation
Answer:
Percentage of seeds that germinated = (Number of seeds germinated / Total number of seeds) × 100
= (8 / 10) × 100 = 80%
(b) Seedlings of cress plants were grown in a Petri dish. A lamp was placed next to the Petri dish, as shown in Fig. 1.2.
(i) Draw an arrow on Fig. 1.2 to predict the direction of continued growth of the seedlings. (Sub-topic: B13.1)
▶️Answer/Explanation
Answer:
The arrow should be drawn pointing towards the light source (from left to right).
(ii) State the name of the growth response to light in plants. (Sub-topic: B13.1)
▶️Answer/Explanation
Answer:
The growth response to light in plants is called phototropism.
(c) Cress plants reproduce by sexual reproduction, which involves gametes. (Sub-topic: B15.2)
(i) Use words or phrases from the list to complete the definition of the term sexual reproduction.
Each word or phrase may be used once, more than once or not at all.
cell walls chromosomes fetus
nuclei sex zygote
Sexual reproduction is a process involving the fusion of the …… of two gametes (…… cells) to form a …… and the production of offspring that are genetically different from each other.
▶️Answer/Explanation
Answer:
Sexual reproduction is a process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote and the production of offspring that are genetically different from each other.
(ii) State the function of the ovary in a plant. (Sub-topic: B15.3)
▶️Answer/Explanation
Answer:
The ovary in a plant contains ovules and is the site of fertilization. It also produces ovules.
(iii) State the name of the male gamete in humans. (Sub-topic: B15.4)
▶️Answer/Explanation
Answer:
The male gamete in humans is called sperm.
Question 2
Calcium is in Group II of the Periodic Table.
(a)(i) An atom of calcium has a proton number (atomic number) of 20 and a nucleon number (mass number) of 40. For this calcium atom, state: (Sub-topic: C2.2)
- the number of neutrons it contains
- its electronic structure
▶️Answer/Explanation
Answer:
– Number of neutrons = 20
– Electronic structure = 2,8,8,2
Explanation:
The number of neutrons is calculated by subtracting the proton number from the nucleon number: 40 – 20 = 20.
The electronic structure is determined by filling the electron shells in order: 2 electrons in the first shell, 8 in the second, 8 in the third, and 2 in the fourth.
(ii) Explain why atoms are electrically neutral. Use ideas about protons and electrons. (Sub-topic: C2.2)
▶️Answer/Explanation
Answer:
Atoms are electrically neutral because the number of protons (positively charged) equals the number of electrons (negatively charged), so the charges cancel out.
Explanation:
In a neutral atom, the positive charge from the protons in the nucleus is balanced by the negative charge from the electrons orbiting the nucleus. This balance ensures that the atom has no net charge.
(iii) State where the neutrons are in an atom. (Sub-topic: C2.2)
▶️Answer/Explanation
Answer:
Neutrons are located in the nucleus of the atom.
Explanation:
The nucleus of an atom contains both protons and neutrons, while electrons orbit the nucleus in electron shells.
(b) The main compound in limestone is calcium carbonate, CaCO3.
(i)State the number of different elements in calcium carbonate. (Sub-topic: C2.4)
▶️Answer/Explanation
Answer:
There are 3 different elements in calcium carbonate.
Explanation:
Calcium carbonate (CaCO3) contains calcium (Ca), carbon (C), and oxygen (O), making a total of 3 different elements.
(ii) Complete the word equation for the reaction between calcium carbonate and dilute hydrochloric acid. (Sub-topic: C6.2)
calcium carbonate + hydrochloric acid → ________ + ________ + ________
▶️Answer/Explanation
Answer:
calcium carbonate + hydrochloric acid → calcium chloride + carbon dioxide + water
Explanation:
The reaction between calcium carbonate and hydrochloric acid produces calcium chloride, carbon dioxide gas, and water. The balanced chemical equation is:
CaCO3 + 2HCl → CaCl2 + CO2 + H2O
(iii) Rainwater is slightly acidic. The acid in rainwater reacts very slowly with limestone rocks. Suggest two reasons for the very slow rate of reaction between rainwater and limestone rocks. (Sub-topic: C6.2)
▶️Answer/Explanation
Answer:
1. The concentration of acid in rainwater is low.
2. The temperature of rainwater is usually low.
Explanation:
The reaction rate is slow because the concentration of acid in rainwater is low, and the temperature of rainwater is generally low, both of which reduce the rate of chemical reactions.
Question 3 (Sub-topic: P1.2)
(a) Fig. 3.1 shows a distance-time graph of a girl’s journey to school.
(i) Write the letter X on part of the graph where the girl is walking fastest.
▶️Answer/Explanation
The girl is walking fastest where the gradient of the graph is steepest. This is typically between t = 500s and t = 800s. Therefore, place the letter X on this part of the graph.
(ii) Write the letter Y on part of the graph where the girl is not moving for a period of time.
▶️Answer/Explanation
The girl is not moving where the graph is horizontal. This is typically between t = 300s and t = 500s. Therefore, place the letter Y on this part of the graph.
(iii) The girl walks a total distance of 400 m in 800 s. Calculate her average speed.
▶️Answer/Explanation
Average speed is calculated using the formula:
\[ \text{Average speed} = \frac{\text{Total distance}}{\text{Total time}} = \frac{400 \, \text{m}}{800 \, \text{s}} = 0.5 \, \text{m/s} \]
Therefore, the girl’s average speed is 0.5 m/s.
(b) At school, the girl places a brick onto a board with a rough surface, and raises one end of the board until the brick moves. Fig. 3.2 shows the angle of the board when the brick starts to move.
(i) Name the force that prevents the brick from moving before the board is raised to 40°.
▶️Answer/Explanation
The force that prevents the brick from moving is friction.
(ii) Suggest how the motion of the brick would be different if a board with a smooth surface was used.
▶️Answer/Explanation
If a board with a smooth surface was used, the brick would move faster or start to move at a shallower angle (less than 40°) because there would be less friction acting against the motion.
(iii) State the type of energy that decreases as the brick moves down the board.
▶️Answer/Explanation
As the brick moves down the board, its gravitational potential energy decreases.
(c) The girl then clamps a ruler to the side of a table as shown in Fig. 3.3.
She applies a force of 40.0 N to the end of the ruler which is 0.27 m from the edge of the table. Calculate the moment of the force about the edge of the table.
▶️Answer/Explanation
The moment of a force is calculated using the formula:
\[ \text{Moment} = \text{Force} \times \text{Distance} = 40.0 \, \text{N} \times 0.27 \, \text{m} = 10.8 \, \text{Nm} \]
Therefore, the moment of the force is 10.8 Nm.
Question 4 (Sub-topic: B16.3)
(a) Huntington’s disease is an inherited disease which damages neurones in the brain.
The disease usually develops between the ages of 30–50.
- The allele for developing Huntington’s disease is dominant, H.
- The allele for not developing Huntington’s disease is recessive, h.
Fig. 4.1 shows the probability of the offspring of cross 1 developing Huntington’s disease.
(i) Complete Fig. 4.1 to show the probability of the offspring of cross 2 developing Huntington’s disease.
▶️Answer/Explanation
The probability of the offspring of cross 2 developing Huntington’s disease is 50%. This is because the cross Hh × hh results in 2 out of 4 offspring having the genotype Hh, which means they will develop the disease.
(ii) Name the type of breeding cross 1 represents.
▶️Answer/Explanation
Cross 1 represents a pure breeding cross, as both parents are homozygous recessive (hh).
(iii) Use the example of the inheritance of Huntington’s disease to state the heterozygous genotype.
▶️Answer/Explanation
The heterozygous genotype is Hh. This means the individual has one dominant allele (H) and one recessive allele (h).
(b) Alleles are versions of genes. Genes are lengths of DNA that code for a protein.
(i) Circle the four elements that are in a protein.
carbon calcium hydrogen oxygen nitrogen water potassium
▶️Answer/Explanation
The four elements in a protein are carbon, hydrogen, oxygen, and nitrogen.
(ii) Describe how to test a substance for protein. Include the positive result.
▶️Answer/Explanation
To test for protein, add Biuret solution to the substance. If the substance contains protein, it will turn purple.
(iii) The boxes on the left show large molecules. The boxes on the right show small molecules.
Draw four lines to link each large molecule with the small molecules they are made from.
▶️Answer/Explanation
Fats and oils are made from fatty acids and glycerol. Glycogen and starch are made from glucose. Protein is made from amino acids.
Question 5
Fig. 5.1 is a pie chart showing the percentages of some of the elements in the Earth’s crust.
(a)(i) Calculate the percentage of aluminium in the Earth’s crust. (Sub-topic: C9.2)
▶️Answer/Explanation
8%
(ii) State the name of the ore from which aluminium is extracted. (Sub-topic: C9.6)
▶️Answer/Explanation
Bauxite
(iii) State the name of the method used to extract aluminium from its ore. (Sub-topic: C9.6)
▶️Answer/Explanation
Electrolysis
(b) Aluminium in the form of a very thin sheet is known as aluminium foil. (Sub-topic: C9.1)
Fig. 5.2 shows aluminium foil being made.
(i) State and describe the physical property of aluminium that allows foil to be made in this way.
▶️Answer/Explanation
Malleability / it is malleable
The idea that it can be forced to change shape without breaking
(ii) Aluminium foil is used to make food containers.
State the chemical property of aluminium that makes it suitable for this use.
▶️Answer/Explanation
Resistant to corrosion / it does not react with food
(c) Alloys containing aluminium are used to make aircraft parts. (Sub-topic: C9.3)
(i) State the meaning of the word alloy.
▶️Answer/Explanation
A (solid) mixture containing metals / a mixture of a metal and other elements
(ii) Aircraft parts are made of aluminium alloys rather than pure aluminium. Suggest why.
Use ideas about physical properties.
▶️Answer/Explanation
Alloy is stronger / less likely to bend or break
(d) Mild steel is an alloy containing iron. (Sub-topic: C9.5)
Mild steel is used to make car bodies.
Car bodies are painted to prevent rusting.
Explain in detail why painting car bodies prevents rusting.
▶️Answer/Explanation
Reference to reaction with / need for oxygen
Reference to reaction with / need for water
Description of paint as a barrier between steel and oxygen / water
Question 6 (Sub-topic: P2.1)
(a) Solids, liquids, and gases have different properties.
Draw two lines from each state of matter to link to two correct properties of matter.
You may draw lines to each property of matter once, more than once, or not at all.
One line has been drawn for you.
▶️Answer/Explanation
Solid: Difficult to compress and fixed shape.
Liquid: Difficult to compress and able to flow.
Gas: Easily compressed and able to flow.
(b) When a liquid is heated, it expands.
(i) Describe how the structure of a liquid-in-glass thermometer is designed to make use of this property.
(ii) When a liquid is heated to a high enough temperature, it starts to boil. State the meaning of the term boiling point.
▶️Answer/Explanation
(i) The liquid is held in a narrow tube. As it is heated, the liquid expands and rises up the tube. The temperature is read from the scale marked on the tube.
(ii) The temperature at which a liquid turns into a gas.
(c) Some materials conduct thermal energy well, and other materials are better thermal insulators.
Complete Table 6.1 by placing a tick (✓) in the correct column for each material.
| Material | Thermal Conductor | Thermal Insulator |
|---|---|---|
| Aluminium | ||
| Copper | ||
| Plastic | ||
| Steel | ||
| Wool |
▶️Answer/Explanation
Aluminium: Thermal Conductor (✓)
Copper: Thermal Conductor (✓)
Plastic: Thermal Insulator (✓)
Steel: Thermal Conductor (✓)
Wool: Thermal Insulator (✓)
(d) State the name of the process that transfers thermal energy from the Sun through the vacuum of space.
▶️Answer/Explanation
Radiation.
(e) (i) Complete the sentence to describe sound waves.
Sound waves transfer …… without transferring matter.
(ii) State the approximate range of audible frequencies for a healthy human ear.
(iii) The pitch and loudness of a sound wave are increased.
State how the amplitude and the frequency of the sound wave change.
▶️Answer/Explanation
(i) Energy.
(ii) From 20 Hz to 20,000 Hz.
(iii) Amplitude increases and frequency increases.
Question 7
Fig. 7.1 shows a food chain.
(a) Table 7.1 shows some of the terms that can be used to describe the organisms in the food chain in Fig. 7.1. (Sub-topic: B18.2)
Complete Table 7.1 by placing ticks (✓) to identify the terms that can be used to describe each organism in this food chain.
| maize | locust | lizard | snake | |
|---|---|---|---|---|
| producer | ||||
| consumer | ||||
| carnivore |
▶️Answer/Explanation
Answer:
| maize | locust | lizard | snake | |
|---|---|---|---|---|
| producer | ✓ | |||
| consumer | ✓ | ✓ | ✓ | |
| carnivore | ✓ | ✓ |
Explanation:
– Maize is a producer because it produces its own food through photosynthesis.
– Locust is a consumer because it feeds on producers (maize).
– Lizard is a consumer and a carnivore because it feeds on other animals (locust).
– Snake is a consumer and a carnivore because it feeds on other animals (lizard).
(b) The Sun is the principal source of energy input to biological systems. (Sub-topic: B18.1)
Describe how energy from the Sun is used to make organic nutrients.
▶️Answer/Explanation
Answer:
Energy from the Sun is used by plants (producers) in the process of photosynthesis to convert carbon dioxide and water into glucose (an organic nutrient). This glucose is then used by the plant for growth and energy, and it also serves as a source of energy for consumers in the food chain when they eat the plants.
Explanation:
– The Sun provides light energy, which is absorbed by chlorophyll in the leaves of plants.
– This energy is used to convert carbon dioxide and water into glucose and oxygen during photosynthesis.
– The glucose produced is an organic nutrient that stores chemical energy, which is then transferred through the food chain as organisms consume each other.
(c) Corn snakes are a type of snake often kept as pets. (Sub-topic: B17.2)
Selective breeding has resulted in bright red-coloured corn snakes.
The sentences below describe the process of selective breeding of bright red corn snakes.
The sentences are not in the correct order.
Use numbers 1–5 to show the correct order.
The third sentence has been identified.
| Sentence | Order |
|---|---|
| Their offspring are observed and bright red snakes identified. | 3 |
| This process is repeated over many generations. | |
| The two bright red corn snakes are bred together. | |
| Two bright red corn snakes are selected. | |
| The bright red offspring are bred. |
▶️Answer/Explanation
Answer:
| Sentence | Order |
|---|---|
| Their offspring are observed and bright red snakes identified. | 3 |
| This process is repeated over many generations. | 5 |
| The two bright red corn snakes are bred together. | 2 |
| Two bright red corn snakes are selected. | 1 |
| The bright red offspring are bred. | 4 |
Explanation:
– Step 1: Two bright red corn snakes are selected.
– Step 2: The two bright red corn snakes are bred together.
– Step 3: Their offspring are observed and bright red snakes identified.
– Step 4: The bright red offspring are bred.
– Step 5: This process is repeated over many generations to ensure the trait is passed on.
Question 8
(Sub-topics: C2.5, C2.4, C12.4)
Water is a compound of the elements hydrogen and oxygen.
(a)(i) State one metallic element that reacts very quickly with water releasing hydrogen gas.
▶️Answer/Explanation
Any Group 1 element (e.g., sodium, potassium).
(ii) The reaction in (a)(i) produces an aqueous solution that has a pH greater than seven. Explain why.
▶️Answer/Explanation
The reaction produces a hydroxide (e.g., NaOH or KOH), which is alkaline, resulting in a pH greater than seven.
(b)(i) Fig. 8.1 shows what happens when a student tests a gas to check that it is hydrogen.
Describe a chemical test the student uses to show that the substance in the test-tube is water.
▶️Answer/Explanation
Test: Use cobalt chloride paper or anhydrous copper(II) sulfate.
Result: Cobalt chloride paper turns from blue to pink, or anhydrous copper(II) sulfate turns from white to blue.
(ii) Balance the equation for the combustion of hydrogen.
▶️Answer/Explanation
2H2 + O2 → 2H2O
(c) Fig. 8.2 is a dot-and-cross diagram of a water molecule.
State the type of chemical bonding in a water molecule.
▶️Answer/Explanation
Covalent bonding.
(d) A student places an aqueous solution of sodium chloride into the apparatus shown in Fig. 8.3.
Water collects in the beaker. Solid sodium chloride remains in the flask.
(i) State the method of separation shown in Fig. 8.3.
▶️Answer/Explanation
Simple distillation.
(ii) Explain why water and sodium chloride can be separated using this method. Use ideas about the types of chemical bond in these compounds.
▶️Answer/Explanation
Water has covalent bonds, which have low boiling points, allowing it to evaporate and condense. Sodium chloride has ionic bonds, which have high boiling points, so it remains solid and does not evaporate.
Question 9
(a) Fig. 9.1 shows visible light rays passing through a thin converging lens onto a screen. (Sub-topic: P3.2.3)
(i) On Fig. 9.1, show the focal length of the thin converging lens using a doubled-headed arrow (←→).
(ii) On Fig. 9.1 label the position of the principal focus of the lens with the letter F.
(iii) Write visible light in the correct position in the electromagnetic spectrum in Fig. 9.2.
(iv) X-rays are used to look at bones in the human body. Describe a safety precaution that is taken when using X-rays.
▶️Answer/Explanation
Answer:
(i) The focal length should be shown as a double-headed arrow from the lens to the principal focus.
(ii) The principal focus should be labeled with the letter F at the point where the light rays converge.
(iii) Visible light should be placed between ultraviolet and infrared in the electromagnetic spectrum.
(iv) A safety precaution when using X-rays is to use lead shielding or wear a lead apron to protect the body from unnecessary exposure to radiation.
(b)(i) X-rays are an example of ionising radiation. State two other examples of ionising radiation. (Sub-topic: P5.2.2)
(ii) State one effect of ionising radiation on living things.
▶️Answer/Explanation
Answer:
(i) Two other examples of ionising radiation are alpha particles and gamma rays.
(ii) One effect of ionising radiation on living things is that it can cause mutations in DNA, leading to cancer or other genetic disorders.
(c) A sample of radioactive material is tested in a hospital laboratory. A detector records the radioactive emissions from the sample. The sample is moved away from the detector. Explain why there is still some radiation detected by the radiation detector. Suggest a source of this radiation. (Sub-topic: P5.2.1)
▶️Answer/Explanation
Answer:
There is still some radiation detected because of background radiation, which is always present in the environment. This radiation can come from natural sources such as cosmic rays, rocks, and even the human body.
Question 10
(Sub-topics: B9.2, B9.3, B9.4)
(a) Fig. 10.1 shows simplified cross-sections of three different types of blood vessel. The artery has been identified.
Complete Fig. 10.1 to identify the other two types of blood vessel.
(b) Table 10.1 shows three organs of the body. The table also shows some of the blood vessels that transport blood to and from these organs.
Complete Table 10.1 to show the main blood vessels to and from these organs.
(c) Fig. 10.2 shows a description that a student has written about the circulatory system.
Circle the two incorrect words in the description.
(d) Plants have specialist tissues for transporting substances. Fig. 10.3 is a simplified cross-section of a plant stem.
(i) Identify the tissue labelled E in Fig. 10.3.
(ii) Name the plant tissue responsible for transporting dissolved sugars.
(iii) Describe where water enters and exits a plant.
▶️Answer/Explanation
10 (a) The other two types of blood vessels are capillaries and veins.
Detailed Solution:
(a) The three main types of blood vessels are arteries, capillaries, and veins. Arteries carry blood away from the heart, capillaries facilitate the exchange of substances between blood and tissues, and veins carry blood back to the heart.
10 (b) Table 10.1 should be completed as follows:
- Heart: Blood transported to the heart by the vena cava and away from the heart by the aorta.
- Lungs: Blood transported to the lungs by the pulmonary artery and away from the lungs by the pulmonary vein.
- Kidney: Blood transported to the kidney by the renal artery and away from the kidney by the renal vein.
Detailed Solution:
(b) The heart receives deoxygenated blood from the body via the vena cava and pumps oxygenated blood to the body through the aorta. The lungs receive deoxygenated blood from the heart via the pulmonary artery and return oxygenated blood to the heart through the pulmonary vein. The kidneys receive blood from the renal artery and return filtered blood to the circulation via the renal vein.
10 (c) The two incorrect words in the description are airways and two-way. The correct words should be blood vessels and one-way.
Detailed Solution:
(c) The circulatory system consists of blood vessels (not airways) that ensure one-way flow of blood (not two-way) due to the presence of valves.
10 (d)(i) The tissue labelled E is the xylem.
Detailed Solution:
(i) The xylem is responsible for transporting water and mineral ions from the roots to the rest of the plant.
10 (d)(ii) The plant tissue responsible for transporting dissolved sugars is the phloem.
Detailed Solution:
(ii) The phloem transports dissolved sugars (such as sucrose) and other nutrients from the leaves to other parts of the plant.
10 (d)(iii) Water enters the plant through the root hairs and exits through the stomata in the leaves.
Detailed Solution:
(iii) Water enters the plant through the root hairs, which increase the surface area for absorption. It exits the plant through the stomata, tiny openings on the underside of leaves that allow for gas exchange and transpiration.
Question 11
(Sub-topics: C11.2, C11.3, C11.4)
Ethane, ethene and ethanol are carbon compounds.
(a) Complete Table 11.1.
▶️Answer/Explanation
11(a) ethene
ethanol
ethane
(b) Fig. 11.1 is a diagram of an industrial process to make ethanol.
(i) Identify substance X.
▶️Answer/Explanation
Substance X is steam (H2O).
(ii) Suggest why a catalyst is needed in the reaction vessel.
▶️Answer/Explanation
A catalyst is needed to increase the rate of the reaction without being consumed in the process. It lowers the activation energy required for the reaction to proceed, making the process more efficient.
(c) Fig. 11.2 shows apparatus and materials a student uses to make ethanol in a school laboratory.
(i) State the name of this process.
▶️Answer/Explanation
The process is called fermentation.
(ii) The student observes a gas bubbling into solution S. Solution S becomes milky. Identify the gas and solution S.
▶️Answer/Explanation
The gas is carbon dioxide (CO2), and solution S is limewater (Ca(OH)2).
(d) Fig. 11.3 shows apparatus the student uses to measure the change in mass when ethanol burns in air.
The mass of the burner and ethanol decreases during the experiment. Suggest why.
▶️Answer/Explanation
The mass decreases because ethanol undergoes combustion, producing carbon dioxide (CO2) and water (H2O) as gaseous products. These gases escape into the air, leading to a loss of mass from the system.
Question 12
(a) Fig. 12.1 shows an electric circuit. (Sub-topic: P4.2.2)
(i) With the switch closed, ammeter \( A_1 \) shows a reading of 0.5A. State the reading on ammeter \( A_2 \).
▶️Answer/Explanation
Answer: 0.5 A
Explanation: In a series circuit, the current is the same at every point. Therefore, the reading on ammeter \( A_2 \) will be the same as the reading on ammeter \( A_1 \), which is 0.5 A.
(ii) A boy measures the potential difference across a resistor in the circuit. Name the instrument the boy uses to measure the potential difference.
▶️Answer/Explanation
Answer: Voltmeter
Explanation: A voltmeter is used to measure the potential difference (voltage) across a component in a circuit. It is connected in parallel with the component.
(b) Fig. 12.2 shows a circuit with two resistors in parallel. (Sub-topic: P4.2.4)
Identify, from the list, the most likely value of the combined resistance of the resistors in parallel. Explain your answer.
2 Ω 4 Ω 8 Ω 16 Ω
▶️Answer/Explanation
Answer: 2 \(\Omega\)
Explanation: The combined resistance of two resistors in parallel is always less than the smallest individual resistance. In this case, the smallest resistance is 2 \(\Omega\), so the combined resistance will be less than 2 \(\Omega\). The formula for the combined resistance \( R \) of two resistors \( R_1 \) and \( R_2 \) in parallel is:
\[ \frac{1}{R} = \frac{1}{R_1} + \frac{1}{R_2} \]
If \( R_1 = 2 \Omega \) and \( R_2 = 4 \Omega \), then:
\[ \frac{1}{R} = \frac{1}{2} + \frac{1}{4} = \frac{3}{4} \]
\[ R = \frac{4}{3} \Omega \approx 1.33 \Omega \]
Thus, the combined resistance is less than 2 \(\Omega\), and the most likely value from the list is 2 \(\Omega\).
(c) Complete the sentences using the words in the list. You can use each word once, more than once or not at all. (Sub-topic: P4.2.4)
current potential difference e.m.f. resistance
The flow of charge in a circuit is called the ……
…… is a measure of the difficulty for a charge to flow in an electrical circuit.
▶️Answer/Explanation
Answer: current, resistance
Explanation: The flow of charge in a circuit is called the current. Resistance is a measure of the difficulty for a charge to flow in an electrical circuit.
(d) One of the wires in the circuit was investigated to see the pattern of the magnetic field around it. On Fig. 12.3 draw the expected pattern and direction of the magnetic field on the square piece of card. (Sub-topic: P4.5.3)
▶️Answer/Explanation
Answer: The magnetic field lines should be concentric circles around the wire, with the direction of the field determined by the right-hand rule (thumb points in the direction of current, fingers curl in the direction of the magnetic field).
Explanation: When current flows through a wire, it generates a magnetic field around the wire. The field lines form concentric circles around the wire, and the direction of the field can be determined using the right-hand rule. If the current is flowing upwards, the magnetic field lines will be clockwise when viewed from above.