Electricity and Magnetism Quiz - ICSE Class 9 Physics
Free practice quiz: Electricity and Magnetism (ICSE Class 9 Physics). 46 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
This ICSE Class 9 Physics practice quiz has 46 multiple-choice questions on Electricity and Magnetism, and 46 of them come with an explanation. Try the 5 sample questions below (tap an option to check yourself), then play the full quiz online. No sign-up needed.
Start quiz: 46 questions, freeSample questions
An electric current of 2 A flows through a resistor of 5 Ω for 10 seconds. What is the heat energy dissipated in the resistor?
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Answer: D. 200 J
The heat energy dissipated in a resistor is given by Joule's law of heating: H = I²Rt, where I is the current, R is the resistance, and t is the time. Given I = 2 A, R = 5 Ω, and t = 10 s, H = (2 A)² * 5 Ω * 10 s = 4 * 5 * 10 = 200 J.
A device converts electrical energy into mechanical energy. Which of the following is an example of such a device?
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Answer: B. Electric Motor
An electric motor uses electrical energy to produce rotational mechanical energy, typically to drive a load. An electric heater converts electrical energy into heat (thermal energy). Incandescent and LED bulbs convert electrical energy into light (radiant energy) and some heat.
A device is rated as 220 V, 100 W. If it is operated at 110 V, what will be its power consumption?
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Answer: C. 25 W
First, calculate the resistance of the device from its rating. Power P = V²/R, so R = V²/P. R = (220 V)² / 100 W = 48400 / 100 = 484 Ω. Now, if the device is operated at 110 V, the new power P' = V'²/R = (110 V)² / 484 Ω = 12100 / 484 = 25 W.
Two resistors, 10 Ω and 20 Ω, are connected in series. What is the voltage drop across the 20 Ω resistor if the total voltage across the combination is 15 V?
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Answer: B. 10 V
In a series circuit, the total resistance is R_total = 10 Ω + 20 Ω = 30 Ω. The total current flowing through the circuit is I = V_total / R_total = 15 V / 30 Ω = 0.5 A. The voltage drop across the 20 Ω resistor is V_20 = I * R_20 = 0.5 A * 20 Ω = 10 V.
A coil of wire has inductance L. If the number of turns in the coil is doubled while keeping the dimensions the same, how does its inductance change?
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Answer: C. It quadruples
The inductance of a solenoid or coil is generally proportional to the square of the number of turns (N²). For a solenoid, L is proportional to N². If the number of turns is doubled (N' = 2N), and other factors remain constant, the new inductance L' will be proportional to (2N)² = 4N². Therefore, L' = 4L. The inductance quadruples.
More questions in this quiz
Answers and explanations are in the full quiz.
- A series circuit consists of three resistors with resistances R₁, R₂, and R₃. If R₁ = 2 Ω, R₂ = 3 Ω, and R₃ = 5 Ω, and the circuit is connected to a 12 V battery, what is the total current flowing through the circuit?
- A parallel circuit has two resistors with resistances R₁ = 4 Ω and R₂ = 6 Ω. If the circuit is connected to a 6 V battery, what is the current flowing through the resistor with resistance R₁?
- A conductor of length 1 m carrying a current of 5 A is placed in a magnetic field of 0.2 T. If the conductor is perpendicular to the magnetic field, what is the force experienced by the conductor?
- What is the equivalent resistance of two resistors, 10 Ω and 20 Ω, connected in parallel?
- When a bar magnet is moved towards a coil, a current is induced in the coil. This phenomenon is known as:
- A wire has a resistance of 10 Ω. If the length of the wire is doubled and the area of its cross-section is also doubled, what will be its new resistance?
- Which of the following statements about magnetic field lines is INCORRECT?
- A 12 Ω resistor is connected in series with a parallel combination of two resistors, each of 6 Ω. What is the total resistance of the circuit?
- If the voltage across a resistor is doubled while its resistance remains constant, the power dissipated by the resistor will:
- A bar magnet is placed near a coil. If the magnet is moved away from the coil, in which direction will the induced current flow in the coil?
- The unit of magnetic flux density is:
- Two wires, X and Y, are made of the same material and have the same length. Wire X has twice the diameter of wire Y. How does the resistance of wire X compare to the resistance of wire Y?
- A battery of 9 V is connected to a resistor. If the current flowing through the resistor is 3 A, what is the power dissipated by the resistor?
- A 60 W bulb and a 100 W bulb are connected in parallel to the mains. Which bulb will glow brighter?
- A resistor has a resistance of R. If three such identical resistors are connected in series, what is their equivalent resistance?
- The magnetic field strength around a long straight wire carrying current is inversely proportional to:
- Which of the following statements about magnetic poles is correct?
- If a conductor of resistance 10 Ω is connected to a battery of 5 V, the current flowing through it is 0.5 A. What is the power dissipated by the resistor?
- Which of the following is NOT a unit of magnetic field strength?
- If a conductor of length 0.5 m carries a current of 10 A and is placed in a magnetic field of 0.4 T at an angle of 30 degrees to the field, what is the magnitude of the force experienced by the conductor?
- A solenoid is wound such that it produces a magnetic field inside. If the number of turns per unit length is doubled, while the current remains the same, how does the magnetic field strength change?
- Which of the following statements about Faraday's Law of Induction is correct?
- A circuit contains a resistor of 5 Ω and an inductor of inductance 0.1 H connected in series to a 12 V DC supply. What is the steady-state current flowing through the circuit?
- If a piece of iron is placed inside a current-carrying solenoid, the magnetic field inside the solenoid will:
- Which phenomenon is demonstrated by an electric generator?
- A wire of resistance 5 Ω is stretched so that its length is doubled. Assuming the volume of the wire remains constant, what is its new resistance?
- What is the unit of magnetic flux?
- If the current through a resistor is halved, and its resistance remains the same, the power dissipated by the resistor will:
- Which of the following is a correct statement regarding electromagnetic waves?
- A parallel circuit has three resistors with resistances 10 Ω, 20 Ω, and 30 Ω. If the total current entering the parallel combination is 6 A, what is the voltage across the parallel combination?
- When a current-carrying conductor is placed in a magnetic field, it experiences a force. This force is perpendicular to both:
- A wire has a resistance R. If its diameter is doubled, while its length and resistivity remain the same, what is its new resistance?
- What is the relationship between the direction of magnetic field lines and the direction of force on a positive charge moving in that field?
- If two resistors of 10 Ω and 20 Ω are connected in parallel to a 6 V battery, what is the current flowing through the 10 Ω resistor?
- Which of the following statements best describes the magnetic field around a bar magnet?
- A conductor of length 0.2 m, carrying a current of 8 A, is placed in a magnetic field of 0.5 T. If the conductor is perpendicular to the field, what is the force experienced by the conductor?
- A device rated 100 W at 200 V is operated on a 100 V supply. What will be the power consumed?
- Which of the following statements about Lenz's Law is correct?
- A generator produces electricity by converting:
- If the voltage across a resistor is kept constant, and its resistance is increased by four times, the current flowing through the resistor will:
- The magnetic field produced by a current loop is strongest:
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