Question

1. which instrument is used for measuring power in an ac circuit? a) ammeter b) wattmeter c) energy meter d) galvanometer 4. the internal resistance of an ideal ammeter is: a) very high b) zero c) infinite d) very low but not zero 5. which instrument uses a moving coil mechanism? a) energy meter b) voltmeter c) ammeter d) both b and c part b: true or false 6. a digital multimeter can measure voltage, current, and resistance. (t/f) 7. a galvanometer can be converted into an ammeter or voltmeter. (t/f) 8. the wattmeter is connected in series with the load to measure power. (t/f) 9. an ohmmeter is used to measure resistance. (t/f) 10. the energy meter measures the total electrical energy consumed over time. (t/f) part c: short answer 11. why must a voltmeter have high resistance? 12. name one instrument that measures frequency in ac circuits. 13. how can a galvanometer be modified to act as a voltmeter? 14. what is the difference between an analog and a digital measuring instrument? 15. write the formula for electrical power in terms of voltage and current.

Explanation:

1. A wattmeter is used to measure power in an AC - circuit. An ammeter measures current, an energy meter measures total energy over time, and a galvanometer is a sensitive current - detecting device.
2. The internal resistance of an ideal ammeter is zero so that it does not affect the current in the circuit it is measuring.
3. Both voltmeters and ammeters can use a moving - coil mechanism.
4. A digital multimeter can measure voltage, current, and resistance.
5. A galvanometer can be converted into an ammeter by connecting a shunt resistor in parallel and into a voltmeter by connecting a high - resistance in series.
6. A wattmeter is connected in both series and parallel (current - coil in series and voltage - coil in parallel) with the load to measure power.
7. An ohmmeter is used to measure resistance.
8. An energy meter measures the total electrical energy consumed over time.
9. A voltmeter must have high resistance so that it draws negligible current from the circuit being measured and does not affect the voltage across the component it is measuring.
10. A frequency counter can measure the frequency in AC circuits.
11. A galvanometer can be modified to act as a voltmeter by connecting a high - resistance in series with it.
12. An analog measuring instrument uses a pointer to indicate the value on a scale, while a digital measuring instrument displays the value in numerical digits.
13. The formula for electrical power in terms of voltage ($V$) and current ($I$) is $P = VI$.

Answer:

1. b) Wattmeter
2. b) Zero
3. d) Both b and c
4. T
5. T
6. F
7. T
8. T
9. To draw negligible current and not affect the measured voltage.
10. Frequency counter
11. Connect a high - resistance in series.
12. Analog uses a pointer on a scale, digital displays numerical digits.
13. $P = VI$