When the direction of current in a conductor is reversed, then the deflection of the needle of the compass placed near a current carrying conductor ____.
A) does not change
B) reverses its direction
C) increases in the same direction
D) decreases in the same direction
When current in a conductor is switched off, the magnetic needle placed near this conductor ____.
A) gets deflected in the reverse direction
B) does not change its position
C) gets back to its initial position
D) will be perpendicular to the length of the conductor
The strength of magnetic field produced by a current carrying solenoid depends upon the ____.
A) current passing through the solenoid
B) direction of the current
C) shape of the solenoid
D) polarity of the solenoid
The strength of magnetic field produced by a current carrying solenoid does not depend upon the ____.
A) number of turns per unit length of the solenoid
B) direction of current
C) nature of the core present inside the solenoid
D) strength of the current
When two bar magnets are kept in contact with their like poles placed together for a long time, they get demagnetised due to the induction of like poles on each other.
Polarity of an electromagnet gets reversed by ____.
A) decreasing the number of turns
B) increasing the number of turns
C) reversing the direction of current
D) switching of current
An electromagnet can be demagnetized by ____.
A) keeping poles together
B) rubbing it
C) switching off the current
D) changing the direction of current
In an electric bell, we use a ____ because the magnetism developed in the rod is ____.
A) soft iron rod, permanent
B) steel rod, permanent
C) soft iron rod, temporary
D) steel rod, temporary
When a steel rod is used in place of a soft iron rod in an electric bell, the ____.
A) frequency of the sound produced is more
B) intensity of the sound produced is more
C) bell does not ring continuously
D) bell rings using less power
Electric motor works on the principle of torque experienced by a current carrying coil in a magnetic field.