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
The filament of an electric bulb is made of______________?
A. carbon
B. aluminium
C. tungsten
D. nickel
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
Instantaneous power in inductor is proportional to the
A. product of the instantaneous current and rate of change of current.
B. square of instantaneous current.
C. square of the rate of change of current.
D Temperature of the inductor.
The instantaneous voltage across the inductor is expressed as the product of inductance and rate of change of current through it. Power is expressed as the product of current and voltage. Hence instantaneous power in an inductor is proportional to the product of instantaneous current and rate of change of current through it.
With rise in temperature the resistance of semi-conductors_________________?
A. decreases
B. increases
C. first increases and then decreases
D. remains constant
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
A. magnetic effect
B. luminous effect
C. thermal effect
D. chemical effect
E. all above effects