Electromagnetism Practice Questions
SPM (Malaysia) · SPM Physics · 148 free MCQs with instant results and detailed explanations.
148
Total
49
Easy
75
Medium
24
Hard
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Sample Questions from Electromagnetism
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Q1
Easy
What is the primary reason a solenoid creates a magnetic field when an electric current flows through it?
A.
The alignment of electric charges in the wire.
B.
The circular motion of electrons around the wire.
C.
The flow of electric current generates a magnetic field around the wire.
D.
The resistance of the wire increases the magnetic effect.
Show Answer & Explanation
Correct Answer: C
A solenoid creates a magnetic field due to the flow of electric current, which generates magnetic lines of force around the wire. This is a fundamental principle of electromagnetism.
Q2
Easy
If the current through a straight conductor is increased, what happens to the magnetic field around the conductor?
A.
The magnetic field strength decreases.
B.
The magnetic field strength remains the same.
C.
The magnetic field strength increases.
D.
The magnetic field disappears.
Show Answer & Explanation
Correct Answer: C
Increasing the current through a straight conductor strengthens the magnetic field around it. According to Ampรจre's Law, the magnetic field is directly proportional to the current.
Q3
Easy
Which of the following devices uses the principle of electromagnetism to operate?
A.
A battery.
B.
An electric fan.
C.
A rubber band.
D.
A light bulb.
Show Answer & Explanation
Correct Answer: B
An electric fan operates on the principle of electromagnetism, where electric current creates magnetic fields that enable the fan blades to rotate, producing airflow.
Q4
Medium
What happens to the magnetic field strength when the distance from a long straight conductor carrying current is doubled?
A.
It doubles.
B.
It remains the same.
C.
It decreases to half.
D.
It decreases to a quarter.
Show Answer & Explanation
Correct Answer: D
The magnetic field strength around a long straight conductor is inversely proportional to the distance from the conductor. When the distance is doubled, the strength decreases to one-fourth of its original value.
Q5
Medium
A solenoid creates a magnetic field when an electric current flows through it. Which of the following factors does NOT affect the strength of the magnetic field inside the solenoid?
A.
Number of turns per unit length
B.
Current flowing through the solenoid
C.
Length of the solenoid
D.
Permeability of the core material
Show Answer & Explanation
Correct Answer: C
The strength of the magnetic field inside a solenoid depends on the number of turns per unit length, the current, and the permeability of the core material, but not on the length of the solenoid itself.
Q6
Medium
A current of 5 A flows through a circular loop of radius 0.1 m. What is the magnetic field strength at the center of the loop (use ฮผ0 = 4ฯ ร 10^-7 Tm/A)?
A.
1 ร 10^-5 T
B.
2 ร 10^-5 T
C.
4 ร 10^-5 T
D.
6 ร 10^-5 T
Show Answer & Explanation
Correct Answer: B
The magnetic field strength at the center of a circular loop is given by B = (ฮผ0I)/(2r). Plugging in the values: B = (4ฯ ร 10^-7)(5)/(2 ร 0.1) results in 2 ร 10^-5 T.
Q7
Medium
In a simple electric motor, what role does the magnetic field play?
A.
It generates electric current.
B.
It provides torque to the rotor.
C.
It converts electrical energy into thermal energy.
D.
It stabilizes the electric supply.
Show Answer & Explanation
Correct Answer: B
In an electric motor, the magnetic field interacts with the current in the rotor to produce a torque, causing the rotor to turn, which is essential for the motor's operation.
Q8
Hard
A long straight conductor carrying a current of 5 A is placed in a magnetic field of strength 0.2 T. If the conductor is 0.5 m long and makes an angle of 30ยฐ with the magnetic field, what is the force acting on the conductor?
A.
0.5 N
B.
0.2 N
C.
0.3 N
D.
0.4 N
Show Answer & Explanation
Correct Answer: A
The force on a current-carrying conductor in a magnetic field is given by F = BILsin(ฮธ). Here, B = 0.2 T, I = 5 A, L = 0.5 m, and ฮธ = 30ยฐ. Thus, F = 0.2 * 5 * 0.5 * sin(30ยฐ) = 0.2 * 5 * 0.5 * 0.5 = 0.5 N.
Q9
Hard
A solenoid with 200 turns and a length of 0.8 m carries a current of 2 A. What is the magnetic field strength inside the solenoid?
A.
0.01 T
B.
0.02 T
C.
0.03 T
D.
0.04 T
Show Answer & Explanation
Correct Answer: B
The magnetic field inside a solenoid is given by B = ฮผโ(nI), where n = N/L and ฮผโ = 4ฯ ร 10^-7 Tm/A. Here, N = 200, L = 0.8 m, I = 2 A. Thus, n = 200/0.8 = 250 turns/m; B = (4ฯ ร 10^-7) * (250) * (2) = 0.02 T.
Q10
Hard
A solenoid of length 0.5 m and radius 0.02 m has 100 turns and carries a current of 3 A. Calculate the magnetic field strength inside the solenoid.
A.
0.1 T
B.
0.12 T
C.
0.15 T
D.
0.18 T
Show Answer & Explanation
Correct Answer: C
The magnetic field strength inside a solenoid is given by B = ฮผโnI, where n = N/L is the number of turns per unit length. Here, N = 100, L = 0.5 m, and I = 3 A. Thus, n = 100 / 0.5 = 200 turns/m. Therefore, B = (4ฯ x 10^-7 Tm/A)(200)(3) = 0.15 T.
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Electromagnetism โ SPM (Malaysia) SPM Physics Practice Questions Online
This page contains 148 practice MCQs for the chapter Electromagnetism in SPM (Malaysia) SPM Physics. The questions are organized by difficulty โ 49 easy, 75 medium, 24 hard โ so you can choose the right level for your preparation.
Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.