Alternating Current — Physics STD 12 Science — Question

1.6 mA current is flowing in conducting wire then the number of electrons flowing per second is

(a) 1011

(b) 1016

(c) 1019

(d) 1015

A copper ring is kept horizontal and a bar of magnet is dropped in the direction of the axis of the ring. The acceleration of the falling magnet will be:

If for a thermocouple  is the neutral temperature,  is the temperature of the cold junction and  is the temperature of inversion, then

(a)

(b)

(c)

(d) None of these

While a collector to emitter voltage is constant in a transistor, the collector current changes by 8.2 mA when the emitter current changes by 8.3 mA. The value of forward current ratio h_fe is

(a) 82

(b) 83

(c) 8.2

(d) 8.3

The maximum peak to peak voltage of an AM wire is 24 mV and the minimum peak to peak voltage is 8 mV. The modulation factor is

(a) 10%

(b) 20%

(c) 25%

(d) 50%

_________ Charge is produced by friction.

Penetrating power of X-rays can be increased by

(a) Increasing the potential difference between anode and cathode

(b) Decreasing the potential difference between anode and cathode

(c) Increasing the cathode filament current

(d) Decreasing the cathode filament current

A horizontal straight conductor kept in north-south direction falls under gravity, then

(a) A current will be induced from South to North

(b) A current will be induced from North to South

(c) No induce e.m.f. along the length of conductor

(d) An induced e.m.f. is generated along the length of conductor

A proton beam is going from north to south and an electron beam is going from south to north. Neglecting the earth's magnetic field, the electron beam will be deflected

During mean life of a radioactive element, the fraction that disintegrates is

(a) e

(b)

(c)

(d)