 |
1 | |
The sensitivity of a galvanometer is determined entirely by its electric resistance. |
|
| | A) | True |
| | B) | False |
|
2 | |
A horizontal current loop that is parallel with a magnetic field directed from right to left will experience a counterclockwise torque if the loop current is counterclockwise when viewed from the top. |
|
| | A) | True |
| | B) | False |
|
3 | |
The magnetic torque on a current loop is a maximum when the angle between the plane of the loop and the magnetic field is 90°. |
|
| | A) | True |
| | B) | False |
|
4 | |
The equation for computing the magnetic torque on a current loop of N turns can also be used for a solenoid of N turns. |
|
| | A) | True |
| | B) | False |
|
5 | |
The radial magnetic field for galvanometer helps to ensure that the pointer deflection will be directly proportional to the current in the coil. |
|
| | A) | True |
| | B) | False |
|
6 | |
Placing a low-resistance wire across the terminals of an ammeter will decrease the range of currents that can be measured. |
|
| | A) | True |
| | B) | False |
|
7 | |
Increasing the multiplier resistance for a voltmeter will increase the range of the voltmeter. |
|
| | A) | True |
| | B) | False |
|
8 | |
Voltmeters must be connected in parallel because of the low multiplier resistance that would short-circuit the circuit if it were placed in series. |
|
| | A) | True |
| | B) | False |
|
9 | |
The proper insertion of an ammeter or a voltmeter into a circuit will alter the current in that circuit slightly, introducing some error. |
|
| | A) | True |
| | B) | False |
|
10 | |
The torque output by a simple dc motor is not uniform. |
|
| | A) | True |
| | B) | False |
|
11 | |
The torque on a solenoid in a magnetic field is not a function of its |
|
| | A) | loop area |
| | B) | number of loops |
| | C) | length |
| | D) | current |
|
12 | |
Which of the following must be a high-resistance instrument? |
|
| | A) | Voltmeter |
| | B) | Ammeter |
| | C) | Motor |
| | D) | Galvanometer |
|
13 | |
The minimum range of a given ammeter is determined by the |
|
| | A) | value of the shunt resistance |
| | B) | value of the multiplier resistance |
| | C) | load resistance |
| | D) | resistance and spring tension in the galvanometer element |
|
14 | |
The torque on a current-carrying loop is a maximum when the plane of the loop |
|
| | A) | is parallel with the magnetic field |
| | B) | is perpendicular to the magnetic field |
| | C) | is at an angle of 45° with the magnetic field |
| | D) | none of the above |
|
15 | |
The range of a dc voltmeter can be increased by |
|
| | A) | increasing the circuit load resistance |
| | B) | increasing the multiplier resistance |
| | C) | decreasing the multiplier resistance |
| | D) | placing a shunt resistance across the voltmeter terminals |
|
16 | |
A galvanometer has an internal resistance of 0.2 Ω and gives a full-scale deflection for a current of 3 mA. What multiplier resistance is required to convert this instrument to a voltmeter whose maximum range is 200 V? |
|
| | A) | 66 Ω |
| | B) | 33 Ω |
| | C) | 3.3 x 104 Ω |
| | D) | 6.67 x 104 Ω |
|
17 | |
If the galvanometer in Question 16 is used to construct an ammeter whose maximum range is 20 A, what shunt resistance must be added? |
|
| | A) | 1 x 10-5 Ω |
| | B) | 3 x 10-5 Ω |
| | C) | 5 x 10-5 Ω |
| | D) | 7 x 10-5 Ω |
|
18 | |
A rectangular coil of wire has a width of 12 cm and a length of 20 cm. The coil is mounted in a uniform magnetic field of flux density 4 x 10-3 T, and a current of 20 A is sent through the windings. If the coil makes an angle of 30° with the field, how many turns of wire will be required to produce an output torque of 0.5 N . m? |
|
| | A) | 100 turns |
| | B) | 200 turns |
| | C) | 300 turns |
| | D) | 400 turns |
|
19 | |
A commercial 5-V voltmeter requires a current of 10 mA to produce full-scale deflection. It can be converted to an instrument with a range of 50 V by adding a multiplier resistance of |
|
| | A) | 9000 Ω |
| | B) | 4500 Ω |
| | C) | 2250 Ω |
| | D) | 1125 Ω |
|
20 | |
A laboratory ammeter has a resistance of 0.1 Ω and reads 3 A full scale. The shunt resistance that must be added to increase the range of the ammeter tenfold is |
|
| | A) | 0.0111 Ω |
| | B) | 0.0011 Ω |
| | C) | 0.022 Ω |
| | D) | 0.0022 Ω |
|
21 | |
The magnetic torque on a current-carrying loop of wire is directly proportional to the of the magnetic field, the of the loop, the in the loop, and the of the angle between the plane of the loop and the magnetic field. |
|
|
|
22 | |
When the plane of the loop is perpendicular to the field, the resultant torque on the loop when it supports a current is . |
|
|
|
23 | |
Any device used for the detection of an electric current is called a(n) . |
|
|
|
24 | |
A voltmeter can be constructed by placing a(n) resistance in series with a(n) . |
|
|
|
25 | |
An ammeter is designed by placing a(n) resistance in with a(n) . |
|
|
|
26 | |
The current reversals required for continuous rotation of the armature in a dc motor are accomplished by using a(n) . |
|
|
|
27 | |
A galvanometer can be used to measure both and . |
|
|
|
28 | |
An ideal ammeter has a(n) resistance, whereas the ideal voltmeter has a(n) resistance. |
|
|
|
29 | |
Three essential parts of a galvanometer are the , , and . |
|
|
|
30 | |
When you insert a voltmeter into a circuit, it must be connected in . An ammeter is connected in . |
|
|