Measurements and Instrumentation

46

The temperature coefficient of resistance for a thermistor is

A. low and negative
B. low and positive
C. high and negative
D. high and positive

47

A moving iron instrument has

A. two iron vanes, one fixed and one movable
B. two movable iron vanes
C. two aluminium vanes, one fixed and one movable
D. two vanes, one fixed made of Aluminium and the other movable made of iron

48

The time base of a high frequency CRO whose screen diameter is 10 cm is set at 10 `mu_` sec/cm. The lowest frequency which can be fully displayed on the screen is

A. more than 100 kHz
B. equal to 100 kHz
C. equal to 10 kHz
D. less than 10 kHz

49

A data signal having frequency components from dc to 50 Hz is to be sent through pulse code modulation using an 8 digit code. The minimum carrier channel bandwidth is

A. 1 kHz
B. 2 kHz
C. 4 kHz
D. 8 kHz

50

Assertion (A): The trigger circuit of a CRO is excited by the same signal as Y plates.

Reason (R): The time base generator develops a saw tooth voltage.

A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not correct explanation of A
C. A is true R is false
D. A is false R is true