Deck 9: Magnetism, Op-Amps, and Sensing Devices

Question 1

A flat coil and solenoid has

A)different fields
B)same physical properties
C)same fields
D)same chemical properties

Answer 1

same fields

Question 2

Flux density is defined by {{}}

A)FIL
B)F⁄(IL)
C)IL
D)I⁄(FL)

Answer 2

F⁄(IL)

Question 3

Strength of magnetic field of solenoid can be increased by adding core made of

A)copper
B)ferrous
C)silver
D)aluminum

Answer 3

ferrous

Question 4

In Fleming's left hand rule, thumb shows direction of

A)current
B)field
C)motion
D)charge

Question 5

If the Earth's magnetic field lines pass through the Hall probe in opposite direction, then the change in reading of voltmeter is

A)thrice the Earth's magnetic flux density
B)four times the Earth's magnetic flux density
C)five times the Earth's magnetic flux density
D)twice the Earth's magnetic flux density

Question 6

LED starts to conduct when voltage is about

A)1 V
B)4 V
C)3 V
D)2 V

Question 7

For non-inverting amplifier the input and output is

A)out of phase
B)in phase
C)have phase difference of 180°
D)have phase difference of 90°

Question 8

A sensing device is also called

A)transistor
B)thermistor
C)sensor
D)transducer

Question 9

Op-amp can provide maximum output current of

A)25 mA
B)30 mA
C)35 mA
D)40 mA

Question 10

Output resistance of an actual op-amp is

A)45Ω
B)46Ω
C)70Ω
D)75Ω

Question 11

Impedance of ideal op-amp is

A)zero
B)1
C)infinite
D)2

Question 12

Change in length and cross-sectional area of metal wire changes

A)current
B)voltage
C)resistance
D)magnetic effect

Question 13

Amplifier produces output with more

A)power only
B)voltage only
C)current only
D)power and voltage

Question 14

Number of power supplies required to get output of op-amp is

A)two
B)four
C)six
D)three

Question 15

A device used to avoid the relay destroying the op-amp is

A)diode
B)LED
C)reverse bias diode
D)forward biased diode

Question 16

As long as op-amp is not saturated, the potential difference between inverting and non-inverting inputs is

A)zero
B)infinite
C)1
D)2

Question 17

A light dependent resistor is made up of

A)low resistance semiconductor
B)low resistance metal
C)high resistance semiconductor
D)high resistance metal

Question 18

In inverting amplifier, the phase difference between input and output voltages must be

A)30°
B)45°
C)90°
D)180°

Question 19

An infinite slew rate refers to

A)no time delay
B)small time delay
C)large time delay
D)variable time delay

Question 20

To limit current in LED, resistor should be connected in

A)parallel
B)series
C)evacuated flask
D)ionized tube

Question 21

A component whose property changes when there is a change in any physical quantity of a device is

A)processor
B)sensor
C)output device
D)portable device

Question 22

Benefits of negative feedback include

A)less distortion
B)increased bandwidth
C)low output resistance
D)all of above

Question 23

When temperature rises, resistance of negative temperature coefficient thermistor

A)increases
B)decreases
C)zero
D)infinity

Question 24

If current of 20 mA is passing through op-amp and voltage drop across series resistor is 10 V then value of resistance is

A)500Ω
B)400Ω
C)300Ω
D)200Ω

Question 25

Graph of resistance of thermistor to temperature is

A)exponential decrease
B)linear decrease
C)exponential increase
D)linear increase