Multiple Choice Questions
Physics: Electricity
Topic: Electricity
Grade: 10
Question 1:
Which of the following statements about electric current is correct?
a) Electric current is the flow of electrons in a circuit.
b) Electric current is the flow of protons in a circuit.
c) Electric current is the flow of both electrons and protons in a circuit.
d) Electric current is the flow of neutrons in a circuit.
Answer: a) Electric current is the flow of electrons in a circuit.
Explanation: Electric current is the flow of charged particles, specifically electrons, in a circuit. Electrons are negatively charged and flow from the negative terminal of a battery to the positive terminal. This flow of electrons creates a flow of charge, which we call electric current. For example, when you turn on a light bulb, electrons flow through the circuit, causing the bulb to light up.
Question 2:
Which of the following materials is a good conductor of electricity?
a) Rubber
b) Glass
c) Plastic
d) Copper
Answer: d) Copper
Explanation: Copper is a good conductor of electricity because it has a high number of free electrons that can easily move through the material. This allows electric current to flow easily through copper wires. In contrast, materials like rubber, glass, and plastic are insulators and do not allow electric current to flow freely.
Example 1: When you plug in an electronic device, such as a toaster, the electric current flows through the copper wires inside the cord to power the device. The copper wires provide a low-resistance path for the current to flow, allowing the toaster to work.
Example 2: In a circuit, if you replace the copper wire with a rubber wire, the electric current will not be able to flow through it, and the circuit will be open. This demonstrates the importance of using a good conductor like copper in electrical circuits.
Question 3:
What happens to the resistance of a wire if its length is doubled?
a) The resistance is halved.
b) The resistance is doubled.
c) The resistance remains the same.
d) The resistance is quadrupled.
Answer: b) The resistance is doubled.
Explanation: The resistance of a wire is directly proportional to its length. When the length of a wire is doubled, the resistance also doubles. This is because as the length increases, the number of collisions between electrons and atoms in the wire also increases, resulting in a higher resistance.
Example 1: If you have a wire with a resistance of 2 ohms and you double its length, the resistance will also double to 4 ohms. This shows the direct relationship between the length of a wire and its resistance.
Example 2: If you have two wires made of the same material but with different lengths, the longer wire will have a higher resistance than the shorter wire. This is because the longer wire offers more obstacles for the flow of electrons, resulting in a higher resistance.