Grade 10 electricity – Introduction to Electricity Quiz
1. What is electricity in the simplest scientific sense?
Electricity is the movement (flow) of electric charge; in solids this is usually the flow of electrons through a conductor.
2. Which particle in an atom is mainly responsible for carrying electric charge in a metal wire?
Electrons are negatively charged and are free to move in metals, forming the electric current when they flow.
3. What is the unit of electrical current?
Current is measured in amperes (A), which indicate the rate of flow of electric charge.
4. Which device is used to measure voltage in a circuit?
A voltmeter measures the potential difference (voltage) between two points in a circuit.
5. What is the relationship between voltage (V), current (I) and resistance (R) expressed by Ohm's law?
Ohm's law states that voltage equals current multiplied by resistance (V = I × R).
6. Which material is a good electrical conductor?
Copper has free electrons and low resistance, so it conducts electricity well and is commonly used for wiring.
7. What is a conductor that is used to protect people from electric shock by providing a low-resistance path to earth called?
The earth wire provides a safe path for fault current to flow to ground, helping prevent electric shock and appliance damage.
8. In Kenya the standard mains supply voltage in a household is approximately:
Kenya uses about 230–240 V AC for household mains, as in many countries following international standards.
9. Which of the following best describes a series circuit?
In a series circuit components share a single path, so the same current flows through each component.
10. What happens to the brightness of bulbs when two identical bulbs are connected in series to a single cell?
In series the total resistance increases, so current decreases and each bulb receives less current, making them dimmer.
11. How should an ammeter be connected in a circuit to measure current correctly?
An ammeter must be placed in series so all the current to the component passes through the instrument for correct measurement.
12. Which of these is the correct unit for electrical resistance?
Resistance is measured in ohms (Ω). It tells how much a material resists the flow of electric current.
13. What is a short circuit?
A short circuit provides a low-resistance route that can cause very large currents, risking overheating, fires, or blown fuses.
14. Which effect is NOT a typical effect of electric current?
Electric current can produce heat, magnetic fields and chemical effects; producing sound without moving parts and without magnetic or mechanical interaction is not a standard effect.
15. What device automatically breaks a circuit when current becomes too large to protect wiring?
Fuses melt and circuit breakers trip when current is too high, interrupting the circuit to prevent damage or fires.
16. What is the correct connection for a voltmeter when measuring the voltage across a lamp in a circuit?
A voltmeter must be connected across (in parallel with) the component to measure the potential difference across it.
17. Which colour combination is used for the protective earth (ground) wire in modern wiring standards?
Modern wiring standards use a green-and-yellow striped conductor for earth/ground to make it easily identifiable for safety.
18. What is the conventional direction of electric current flow?
By convention, electric current is shown flowing from positive to negative, even though electrons actually move from negative to positive.
19. Which instrument would you use to measure the resistance of a resistor in a school lab?
An ohmmeter or a multimeter on the resistance setting is used to measure the resistance of a component directly.
20. If a kettle uses 2000 W (watts) of power on 240 V supply, what is the current drawn (approx)?
Current I = P ÷ V = 2000 W ÷ 240 V ≈ 8.33 A. This shows how power, voltage and current are related.
21. What is the most likely result if you connect the positive terminal of a cell directly to its negative terminal with a thick wire?
Connecting terminals directly creates a short circuit with very low resistance, causing a large current that can overheat and damage the cell.
22. Which statement about insulators is correct?
Insulators (like rubber, glass, dry wood) have very few free charges and so prevent the flow of electric current.
23. Why is earthing important in homes and appliances?
Earthing gives stray or fault currents a low-resistance path to ground, reducing shock risk and allowing protective devices to operate.
24. Which energy unit does your electricity bill use for household consumption?
Electricity consumption on bills is measured in kilowatt-hours, the energy used by a 1 kW device running for 1 hour.
25. Which of the following is a safe practice when using electrical appliances at home?
Keeping appliances dry and unplugging before cleaning prevents electric shock and reduces the risk of damage—unlike the unsafe options listed.
26. What is meant by the term 'static electricity'?
Static electricity refers to stationary charges that accumulate on surfaces, often discharged suddenly as a spark.