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CIE iGCSE Co-Ordinated Science P4.2.1 Electrical charge Exam Style Questions Paper 1

CIE iGCSE Co-Ordinated Science Paper 1 - All Chapters

Question

A student holds an iron rod in one hand and a dry cotton cloth in the other hand. The student rubs the iron rod with the cotton cloth several times. Next the student holds the cloth close to the iron rod.

The student then repeats this procedure with an identical dry cotton cloth and a plastic rod.

Which row shows the force between the iron rod and cloth and between the plastic rod and cloth when they are held close to each other after rubbing?

▶️ Answer/Explanation

When two materials are rubbed together, electrons can be transferred from one material to the other, causing them to become charged (electrostatic charging by friction).

Iron rod with cotton cloth: Iron is a conductor. When the student rubs the rod and then holds it, the charge that builds up on the rod can flow to the student’s hand (through the rod). This means the rod and cloth do not remain charged and thus exert no force on each other when held close. The student and the cloth may become charged, but the force is between the rod and cloth, not the student and cloth.

Plastic rod with cotton cloth: Plastic is an insulator, so charge cannot flow through it. When rubbed, electrons are transferred from the cotton cloth to the plastic rod (or vice versa, depending on the materials). This leaves the plastic rod charged and the cloth charged with the opposite charge. Since opposite charges attract, there will be an attraction between the plastic rod and the cloth when held close.

Therefore, the force between the iron rod and cloth is no force, and the force between the plastic rod and cloth is attraction. This matches row B.

✅ Answer: (B)

Question

Two charged rods X and Y repel each other.

Which row gives a possible description of how the rods became charged?

▶️ Answer/Explanation
Two charged rods only repel each other if they carry the same type of charge, either both positive or both negative.
Charging by friction works by transferring electrons from one material to another, never by transferring positive charge.
The material that loses electrons becomes positively charged, while the material that gains electrons becomes negatively charged.
Row A is the only description in which both rods end up with the same sign of charge, consistent with a repulsive force.
✅ Answer: (A)

Question

When two different, uncharged, insulating materials are rubbed together, one becomes positively charged and the other becomes negatively charged.

What happens to cause the materials to become charged?

▶️ Answer/Explanation
Rubbing two insulating materials together transfers electrons from one material’s surface to the other.
The material that loses electrons becomes positively charged, since it now has more protons than electrons.
The material that gains those electrons becomes negatively charged, since it now has more electrons than protons.
✅ Answer: (C)

Question

Three charged balls P, Q and R are suspended by insulating threads. Ball P is negatively charged.

Ball Q is brought close to ball P. The balls move away from each other.

Ball Q is now brought close to ball R. The balls move closer to each other.

What are the signs of the charges on ball Q and ball R?

▶️ Answer/Explanation
Ball P is negatively charged, and it moves away from ball Q, so like charges must be repelling — meaning ball Q is also negatively charged.
When ball Q is brought close to ball R, the balls move closer together, showing attraction, which only happens between unlike charges.
Since Q is negative, ball R must be positively charged for attraction to occur.
✅ Answer: (B)

Question

A plastic rod is rubbed with a cloth. The rod becomes positively charged.
Which statement describes why this happens?

A. Electrons move from the cloth to the rod.
B. Electrons move from the rod to the cloth.
C. Protons move from the cloth to the rod.
D. Protons move from the rod to the cloth.

▶️ Answer/Explanation
Charging by friction always involves the transfer of electrons, since protons are fixed within the nucleus and cannot move between objects.
If the rod becomes positively charged, it must have lost negative charge, meaning electrons have moved away from it.
These electrons transfer from the rod onto the cloth, leaving the rod with an overall positive charge.
✅ Answer: (B)
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