A light bulb operating at 110 v draws 1.40 a of current. what is its resistance?

                                  Chapter 18  Sample Multiple Choice Problems

1.       How much charge must pass by a point in 1.5 s for the current to be 2.0 A?

          a.       0.75 C

          b.       1.0 C

          c.       2.0 C

          d.       3.0 C

2.       What potential difference is required to cause 2.0 A to flow through a resistance of 8.0 Ω?

          a.       0.25 V

          b.       4.0 V

          c.       6.0 V

          d.       16 V

3.       What is 1 Ω equivalent to?

          a.       1 J/s

          b.       1 W/A

          c.       1 VúA

          d.       1 V/A

4.       A light bulb operating at 110 V draws 1.40 A of current.  What is its resistance?

          a.       12.7 Ω

          b.       78.6 Ω

          c.       109 Ω

          d.       154 Ω

5.       If the resistance in a constant voltage circuit is doubled, the power dissipated by that circuit will

          a.       increase by a factor of two.

          b.       increase by a factor of four.

          c.       decrease to one-half its original value.

          d.       decrease to one-fourth its original value.

6.       A 500-W device is connected to a 100-V power source.  What current flows through this surface?

          a.       50,000 A

          b.       0.20 A

          c.       5.0 A

          d.       100 A

7.       A lamp uses a 150-W bulb.  If it is used at 120 V, what is its resistance?

          a.       48 Ω

          b.       96 Ω

          c.       80 Ω

          d.       150 Ω

8.       A 200-Ω resistor is rated at 1/4 W.  What is the maximum current it can draw?

          a.       0.035 A

          b.       0.35 A

          c.       50 A

          d.       0.25 A

9.       A 100-W driveway light bulb is on 10 hours per day.  Assuming the power company charges 10 cents for each kilowatt-hour of electricity used, estimate the annual cost to operate the bulb.

          a.       $3.65

          b.       $7.30

          c.       $36.50

          d.       $73.00

10.     If the voltage across a circuit of constant resistance is doubled, the power dissipated by that circuit will

          a.       quadruple.

          b.       double.

          c.       decrease to one half.

          d.       decrease to one fourth.

11.     If the current flowing through a circuit of constant resistance is doubled, the power dissipated by that circuit will

          a.       quadruple.

          b.       double.

          c.       decrease to one half.

          d.       decrease to one fourth.

12.     A toaster is rated 800 W at 120 V.  What is the resistance of its heating element?

          a.       16 Ω

          b.       18 Ω

          c.       6.7 Ω

          d.       0.15 Ω

13.     4.00 A is flowing through an 8.00 Ω resistor.  How much power is being dissipated?

          a.       32.0 W

          b.       128 W

          c.       256 W                                        

          d.       1.02 kW

14.     What is 1 W equivalent to?

          a.       1 V/A

          b.       1 Ω A

          c.       1 V A

          d.       1 V/Ω

15.     A kilowatt-hour is equivalent to

          a.       1000 W

          b.       3600 s

          c.       3,600,000 J/s

          d.       3,600,000 J

Answers:

1.       d

2.       d

3.       d

4.       b

5.       c

6.       c

7.       b

8.       a

9.       c

10.     a

11.     a

12.     b

13.     b

14.     c

15.     d