Home Chapter 21 Practice Questions

# Practice Questions

This activity contains 25 questions.

## The metal rod in the figure is sliding along a U-shaped track as shown. There is a magnetic field in the blue region which is into the figure. What is the direction of the current in the sliding rod?

 UP DOWN

## In the above question, if B = 0.4T, L = 0.5 m and v = 3 m/s, what is the magnitude of the induced EMF?

 3 volts 2.6 volts 0.6 volts 0 volts

## If the total resistance in the circuit in Questions 1 and 2 at a given time is 0.01 ohms, what will be the induced current?

 0.6 amps 6 amps 60 amps 600 amps

## In Questions 1, 2, and 3 what would be the total magnetic field into the page 12 mm to the left of the moving rod and still in the blue region?

 .4 T .399 T .401 T 0 T

## A B In which of the above, if any, is the induced current up?

 A only B only A and B Neither

## The current in the wire on the right is increasing, What is the direction of the induced current in the wire loop on the left?

 clockwise counter-clockwise

## The current in the wire on the right is decreasing. What is the direction of the induced current in the wire loop on the left?

 clockwise counter-clockwise

## If the current in the dark wire loop is counter-clockwise and increasing, what is the direction of the induced current in the smaller loop in its middle?

 clockwise counter-clockwise

## What will be the direction of the induced current in the small outer loop in the previous question?

 clockwise counter-clockwise

## A transformer has an input of 110 DC volts, with 100 turns on the primary and 10 turns on the secondary. What is the output voltage?

 1100 volts 110 volts 11 volts 0 volts

## 120 volt house current is to be transformed down to 12 volts. What is the ratio of the primary to secondary turns?

 20-1 10-1 1-10 1-20

## In the preceeding question, if the input current (RMS) is 1.5 amps then the output current is

 0.015 amps 0.15 amps 1.5 amps 15 amps

## A transformer takes 10 volts and 5 amps (both RMS) and changes it to 150 volts. What is the power output of the transformer?

 5 watts 50 watts 150 watts 1500 watts

## A transformer has 150 turns on the primary and 20 on the secondary. 100 volts and 10 amps will be changed to

 13.3 volts and 1.33 amps. 13.3 volts and 75 amps. 750 volts and 1.33 amps. 750 volts and 75 amps.

## 50 kW are to be transmitted over wires with a resistance of 1.8 ohms at 300 volts. What is the power loss in the wires?

 50 kW 5 kW 5 W 0 W

## 50 kW are to be transmitted over wires with a resistance of 1.8 ohms at 30000 volts. What is the power loss in the wires?

 50 kW 5 kW 5 W 0 W

Close the switch in the above circuit by pressing the button below and find the time constant of the circuit.
 t= seconds I= amps

 3 s 6 s 9 s 12 s

## What is the resistance in the circuit in Question 17?

 1 ohm 10 ohms 50 ohms 100 ohms

## What is the inductance in the circuit in Question 17?

 3.33 H 10 H 20 H 30 H

The above circuit is discharged by flipping the switch. What is its time constant?
 t= seconds I= amps

 2 s 4 s 6 s 8 s

## What is the resistance in the circuit in Question 20?

 20 ohms 15 ohms 10 ohms 5 ohms

## What is the inductance in the circuit in Question 20?

 10 H 20 H 30 H 40 H

The following data windows control the above LCR circuit. You can select different values for R and change the frequency by entering new values for f and pressing TAB. What is the resonant frequency of this circuit?
 R= 10 100 1000 10000 ohms frequency: Hz I= amps

 112 Hz 224 Hz 232 Hz 238 Hz 242 Hz 275 Hz

## What is the voltage in the circuit in Question 23?

 10 volts 50 volts 100 volts 120 volts

## If the inductance in the circuit in Question 23 is 30 mH, what is the capacitance?

 10 microF 15 microF 20 microF 30 microF