Class 10 Physics Unit-15: Electromagnetism, Solved MCQs With Verified Answers. (National Book Foundation 2022 as Federal Text Book, Islamabad)

1. If a magnetic field in a conductor, passing perpendicularly through cardboards is anticlockwise then the direction of current in it due to free electrons is

(a) out of page
(b) into the page
(c) upward
(d) downward

... Answer is (d) downward
Using the Left hand instead of the right hand for current due to electrons. (The question is not clear. If you have a different answer please write in the comments below)

2. According to the Right hand-palm rule fingers indicate

(a) conventional current
(b) emf
(c) magnetic force
(d) magnetic field

... Answer is (d) magnetic field
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3. A conductor is placed horizontally, the direction of the current in it is in the east, and the magnetic field is out of the page, perpendicular to the conductor. What is the direction of the magnetic force on the conductor?

(a) east
(b) west
(c) south
(d) north

... Answer is (d) north
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3. Direction of the magnetic field inside the permanent bar magnet is:

(a) from north to south
(b) from south to north
(c) from east to south
(d) from west to north

... Answer is (b) from south to north
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4. Which of the following parts is responsible for the DC motor coil to rotate in one direction?

(a) load
(b) slip rings
(c) commutators
(d) battery

... Answer is (c) commutators
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5. If a coil moves parallel to a uniform magnetic field, the induced emf will be:

(a) maximum
(b) zero
(c) negative
(d) positive

... Answer is (b) zero
Since the flux is zero, so there will be no emf induced in the coil.

6. The device which converts mechanical energy into electrical energy :

(a) motor
(b) generator
(c) thermocouple
(d) battery

... Answer is (b) generator
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7. Step-up transformer increases:

(a) current
(b) power
(c) energy
(d) voltage

... Answer is (d) voltage
-----------------

8. . What is the output of a step-up transformer having a turns ratio of 1:50, if 50 V DC is applied at its primary coil?

(a) 2500 V
(b) 1 V
(c) zero
(d) 100 V

... Answer is (b) 1 V
`\frac {V_s}{V_p}` = `\frac {N_s}{N_p}`
 

9. If the magnet is moved towards the coil with uniform acceleration, the magnitude of induced emf in the coil:

(a) increases
(b) decreases
(c) remain same
(d) is zero

... Answer is (c) remain same
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10. If a transformer has 100 turns in the primary and 500 turns in the secondary if 6 volts are applied across its primary the voltage induced across its secondary would be

(a) 0 volts
(b) 30 volts
(c) 45 volts
(d) 60 volts

... Answer is (b) 30 volts
`\frac {V_s}{V_p}` = `\frac {N_s}{N_p}`

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