When electric current passes through a metallic conductor, its temperature rises. This is due to__________?
(A) collisions between conduction electrons and atoms
(B) the release of conduction electrons from parent atoms
(C) mutual collisions between metal atoms
(D) mutual collisions between conducting electrons
If the efficiency of a machine is to be high, what should be low __________?
(A) Input power
(B) Losses
(C) True component of power
(D) kWh consumed
(D) Ratio of output to input
Resistance of a material always decreases if___________?
(A) temperature of material is decreased
(B) temperature of material is increased
(C) number of free electrons available become more
(D) none of the above is correct
Electric current passing through the circuit produces_____________?
(A) magnetic effect
(B) luminous effect
(C) thermal effect
(D) chemical effect
(D) all above effects
A field of force can exist only between_____________?
(A) two molecules
(B) two ions
(C) two atoms
(D) two metal particles
When resistance element of a heater fuses and then we reconnect it after removing a portion of it, the power of the heater will___________?
(A) decrease
(B) increase
(C) remain constant
(D) none of the above
Copper wire of certain length and resistance is drawn out to three times its length without change in volume, the new resistance of wire becomes__________?
(A) 1/9 times
(B) 3 times
(C) 9 times
(D) unchanged
74. Sparking occurs when a load is switched off because the circuit has high_________?
(A) resistance
(B) inductance
(C) capacitance
(D) impedance
Switching of a lamp in house produces noise in the radio. This is because switching operation produces________?
(A) arcs across separating contacts
(B) mechanical noise of high intensity
(C) both mechanical noise and arc between contacts
(D) none of the above
For testing appliances, the wattage of test lamp should be_____________?
(A) very low
(B) low
(C) high
(D) any value