Chapter 18: Direct-Current Circuits

Question 1

ammeter

Answer 1

measures current (I)

Question 2

voltmeter

Answer 2

measures voltage (potential difference) (▲V); connects to the two contacts of the bulb

Question 3

in series

Answer 3

resistors are connected end-to-end

Question 4

in series, the current is ____ in all resistors

Answer 4

the same

Question 5

▲V= IR1 + IR2 = I(R1 + R2)

Answer 5

resistors in series

I= current
▲V= potential difference (voltage) 
R= resistance

Question 6

equation for potential difference for resistors in a series

Answer 6

▲V= IR1 + IR2 = I(R1 + R2)

Question 7

(stopped at slide 6/21)

Answer 7

.

Question 8

A toaster is designed to operate with a voltage of 120 V, and a clothes dryer is designed to operate with a voltage of 240 V. Based solely on this information, which appliance uses more power?
Select one:
a. The dryer
b. The toaster
c. Insufficient information is given for an answer

Answer 8

Insufficient information is given for an answer

Question 9

In order to calculate the fraction of the total power delivered to the load resistor in a circuit consisting of a battery and a load resistor, one needs to know only the
Select one:
a. emf, load resistance, and internal resistance.
b. load resistance and internal resistance.
c. load resistance.
d. internal resistance.

Answer 9

load resistance and internal resistance.

Question 10

In the figure below, the current is measured with the ammeter at the bottom of the circuit. When the switch is opened, the reading on the ammeter

Select one:

a. decreases.
b. Zero
c. does not change.
d. increases.

Answer 10

decreases

Question 11

In the figure below, the current is measured with the ammeter on the right side of the circuit diagram. When the switch is closed, the reading on the ammeter

Select one:

a. does not change.
b. Zero
c. increases.
d. decreases.

Answer 11

increases.

Question 12

Kirchhoff's loop rule is equivalent to which of the following principles?
Select one:
a. conservation of force
b. conservation of mass
c. conservation of charge
d. conservation of energy

Answer 12

conservation of energy

Question 13

Why does a battery get warm while in use?
Select one:
a. Because of internal resistance, power is delivered to the battery material, raising its temperature.
b. Batteries actually cool down when in use.
c. The electrons in the wire build up inside the battery, thus heating it.
d. None of these options.

Answer 13

Because of internal resistance, power is delivered to the battery material, raising its temperature.