Chapter-7 Electricity — Online MCQ Test
SCIENCE · Samacheer Kalvi 9th · Tamil Nadu State Board
Practice Chapter-7 Electricity with a free chapter-wise online MCQ test.
This chapter covers: Description Covers electric circuits Ohm's law resistance and electrical applications Keywords Current Resistance Circuit Ohms Law Electricity.
AI-generated questions from basic to board-exam level, with instant results and explanations.
Chapter-7 Electricity — Important Questions & Answers
What is the SI unit of electric current?
- A. Volt
- B. Ampere
- C. Ohm
- D. Watt
Answer: B. Ampere
The SI unit of electric current is ampere (A). It measures the rate of flow of electric charge.
The SI unit of electric current is ampere (A). It measures the rate of flow of electric charge.
Which device is used to measure electric current in a circuit?
- A. Voltmeter
- B. Ammeter
- C. Galvanometer
- D. Resistor
Answer: B. Ammeter
An ammeter is connected in series to measure current flowing through a circuit.
An ammeter is connected in series to measure current flowing through a circuit.
If the potential difference across a resistor is doubled while its resistance remains the same, the current will:
- A. Become half
- B. Remain the same
- C. Double
- D. Become four times
Answer: C. Double
From Ohm's law, I = V/R. If V doubles and R is constant, the current also doubles.
From Ohm's law, I = V/R. If V doubles and R is constant, the current also doubles.
A student increases the length of a wire but keeps its material and thickness the same. What happens to its resistance?
- A. It decreases
- B. It increases
- C. It becomes zero
- D. It remains unchanged
Answer: B. It increases
Resistance is directly proportional to the length of a wire. So, increasing length increases resistance.
Resistance is directly proportional to the length of a wire. So, increasing length increases resistance.
A bulb glows dimly in a circuit. Which of the following is the most likely reason, based on Ohm's law?
- A. The circuit has no resistance
- B. The current through the bulb is low
- C. The voltage is infinite
- D. The switch is always off
Answer: B. The current through the bulb is low
A dim bulb indicates less current through the filament. Lower current usually means lower brightness.
A dim bulb indicates less current through the filament. Lower current usually means lower brightness.