iGCSE Physics (0625) 4.2.5 Electrical energy and electrical power -Exam Style Questions Paper 1 - New Syllabus
▶️ Answer/Explanation
Detailed solution:
First, convert the power from watts to kilowatts: $2200 \text{ W} = 2.2 \text{ kW}$.
Next, convert the time from minutes to hours: $48 \text{ minutes} = 48/60 = 0.8 \text{ hours}$.
Calculate the energy used in kilowatt-hours: $\text{Energy} = \text{Power} \times \text{Time} = 2.2 \text{ kW} \times 0.8 \text{ h} = 1.76 \text{ kWh}$.
Finally, determine the total cost: $\text{Cost} = 1.76 \text{ kWh} \times \$0.25/\text{kWh} = \$0.44$.
This confirms that the correct answer is Option A.
▶️ Answer/Explanation
Detailed solution:
To find the energy transferred, use the formula E=V×I×t, where V is voltage, I is current, and t is time.
Substitute the given values into the equation: E=12 V×2.0 A×60 s.
Calculating the product gives E=1440 J.
Among the given choices, 1400 J is the closest approximate value.
Therefore, the correct choice is Option D.
▶️ Answer/Explanation
Detailed solution:
The battery stores chemical energy and transfers it as electrical energy to the circuit.
The lamp converts this electrical energy into light and thermal energy.
The thermal energy is dissipated to the surrounding air, completing the energy transfer pathway.
This matches the sequence: battery \(\rightarrow\) lamp \(\rightarrow\) surrounding air.
Therefore, Option A is correct.