Q: For two capacitors $$C_1$$ and $$C_2$$ connected in series, which equation gives the equivalent capacitance $$C_S$$?

$$C_S = \frac{C_1$ \times C_2$}{C_1$ + C_2$}$$

Q: A galvanometer with a coil resistance $$R_C = 50 \Omega is $$used to measure a current of 60.0 mA. What shunt resistance $$R$$ should be used if the galvanometer's full-scale limit is 0.100 mA?

$$8.35 \times 10$$^{-2}$$ \Omega$$

Question 1

Which equation correctly represents the equivalent capacitance $$C_P$$ for two capacitors $$C_1$$ and $$C_2$$ connected in parallel?

Accepted Answer

$$C_P = C_1$ + C_2$

Question 2

For two capacitors $$C_1$$ and $$C_2$$ connected in series, which equation gives the equivalent capacitance $$C_S$$?

Accepted Answer

$$C_S = \frac{C_1$ 	imes C_2$}{C_1$ + C_2$}$$

Question 3

A 2.7 $$\muF $$and a 4.2 $$\muF $$capacitor are connected in series across a 200 V source. What is the energy stored in the system?

Accepted Answer

$$0.032 J$$

Question 4

A 2.7 $$\muF $$and a 4.2 $$\muF $$capacitor are connected in parallel across a 200 V source. What is the energy stored in the system?

Accepted Answer

$$0.14 J$$

Question 5

Given the network in the image with capacitors of 5.0 $$\muF$$, 24 $$\muF$$, 4.0 $$\muF$$, 12 $$\muF$$, 6.0 $$\muF$$, and 8.0 $$\muF$$, what is the equivalent capacitance between points A and B?

Accepted Answer

$$2.0$$ $$\muF$$

Question 6

Which device is used to measure current in a circuit and must be connected in series?

Accepted Answer

Ammeter

Question 7

Why must an ammeter have very low resistance?

Accepted Answer

To minimize its effect on the circuit by acting as a series resistor

Question 8

Why must a voltmeter have very high resistance?

Accepted Answer

To minimize its effect on the circuit by acting as a parallel resistor

Question 9

A galvanometer with a coil resistance $$R_C = 50 \Omega is $$used to measure a current of 60.0 mA. What shunt resistance $$R$$ should be used if the galvanometer's full-scale limit is 0.100 mA?

Accepted Answer

$$8.35 	imes 10$$^{-2}$$ \Omega$$

Question 10

A galvanometer with a coil resistance $$R_C = 50 \Omega is $$used to measure a voltage of 10.0 V. What series resistance $$R$$ should be used if the galvanometer's full-scale limit is 0.100 mA?

Accepted Answer

$$105 \Omega$$

Question 11

A 1800 W heater is powered by a 120 V supply. What is the minimum wire gauge required for the extension cord, based on current rating?

Accepted Answer

14 gauge

Question 12

Why are smaller-gauge wires recommended for high-power appliances?

Accepted Answer

They have lower resistance and can carry more current

Question 13

A circuit has a 10 A fuse. Three appliances are connected in parallel: 500 W, 200 W, and 100 W. If the supply voltage is 120 V, will the fuse blow?

Accepted Answer

No, because the total current is 6.7 A

Question 14

What is the primary purpose of grounding electrical devices?

Accepted Answer

To reduce the danger of electric shock

Question 15

If a wire inside a heater touches the metal casing and the device is not properly grounded, what is the most likely consequence?

Accepted Answer

The user may receive an electric shock

Question 16

Which equation gives the energy stored in a capacitor?

Accepted Answer

$$E = \frac{1}{2}CV^2$

Question 17

When measuring voltage across a resistor in a circuit, why does a voltmeter with high resistance have little effect?

Accepted Answer

Because its resistance is much higher than the resistor being measured, so almost all current flows through the resistor

Question 18

Which of the following statements about fuses is correct?

Accepted Answer

Fuses melt and open the circuit if too much current is drawn

Question 19

A galvanometer is used as a voltmeter by adding a resistor in series. What is the effect of increasing the series resistance?

Accepted Answer

It decreases the current through the galvanometer

Lec 9

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