Question

What is the total power in a circuit if the resistance is 800 and the voltage is 60 VDC?
A. 4.5 W
B. 13.33 W
C. 120 W
D. 48 W
User:
A circuit contains six 20 resistors connected in series. What is the total circuit resistance?
A. 60
B. 3.33
C. 6
D. 120
User:
What circuit quantity is measured by connecting a meter's test leads in series with an energized component?
A. Voltage
B. Current
C. Power
D. Resistance

Answer 1

1.)    Power, P  =  V²/R  =  800²/45 =  4.5 W  (A).

2.)  Six Resistors in Series.
R = R1 + R2 + R3 + R4 + R5 + R6,    Since R is the same, R = 20

R total = 6*20 = 120 (D)

3.)  It is the current.  Series connection is to evaluate current.  (B)

Answer 2

1. A. 4.5 W

The power in a circuit is given by:

$P=\frac{V^2}{R}$

where V is the voltage and R is the resistance.

In this circuit, we have:

$V=60 V$ is the voltage

$R=800 \Omega$ is the resistance

Therefore, the power in the circuit is

$P=\frac{(60 V)^2}{800 \Omega}=4.5 W$

2. D. $120 \Omega$

The total resistance of resistors connected in series is the sum of the individual resistances:

$R_T = R_1 +R_2 +R_3 +...$

In this case, we have 6 identical resistors with same resistance $R=20 \Omega$. Therefore, the total resistance will be

$R_T = 20 \Omega +20 \Omega +20 \Omega +20 \Omega +20 \Omega +20 \Omega =120 \Omega$

3. B. Current

An ammeter is a device which is put in series with another component of the circuit, in order to measure the current through it. In fact, in a circuit, components which are connected in series have the same current flowing through them: therefore, the reading of the current in the ammeter will corresponds to the same current which is flowing to the other component.