Popquiz about current?

(Current-7)

Current flows through a light bulb. Suppose a wire is connected across the bulb as shown. When this wire is connected...


A: All the current continues to flow through the bulb

B: Half the current flows through the bulb, half through the wire

C: All the current flows through the wire.


(Current-5)

US Bulbs are rated for 120 V. European bulbs are designed for 240 V.

If you buy a 100 W light bulb as a souvenir in Paris, and plug it in at home, what happens?

A: It glows as usual, like a 100 W bulb should.

B: Bzzzt, it burns out, too much power

C: It glows half as bright (powerful) as usual

D: It glows 1/4 as bright as usual

E: None of these/not enough info/don't know.


(Current hmy-1)

Electric companies generally tell their power customers the # of kilowatt-hours consumed in a month.

What quantity is the power company telling you?

A: power, duh!

B: energy / time

C: time

D: energy

E: None of these/impossible to determine

F: current


(Current_hmy-04)

Rank in order, from largest to smallest, the powers dissipated in resistors a to d.

R, DV

+

-

R, 2DV

+

-

2R, DV

+

-

½ R, DV

+

-


a

b

c

d

1. a , b, c, d

2. b, d, a, c

3. b, c, a=d

4. a=d, c, b

5. b, d, b, c

(Circuits-01)

A battery with voltage ("emf") of 5V is attached to a resistor of resistance R. The circuit diagram is shown below. The point A is at zero volts.

I) The correct voltages at the points B, C, and D are:

A: VB = 0, VC = 5, VD = 0

B: VB = 5, VC < 5, VD> 0

C: VB = 5, VC < 5, VD= 0

D: VB = 5, VC = 5, VD=0

E: None of these.

II) Which way does the current flow in this circuit?

A: Clockwise

B: Counterclockwise

C: Not enough information given

(Circuits-06)

I) What is the "equivalent resistance" of this circuit?

A: 1 W

B: 2 W

C: 3 W

D: 4 W

E: None/???

II) What is the current flowing through resistor R2?

A: 1.5 A

B: 2 A

C: 3 A

D: 4 A

E: 12 A


(Circuits-07)

I) What is the "equivalent resistance" of this circuit?

A: 1 W

B: 2 W

C: 3 W

D: 4 W

E: None/???

II) What is the current flowing through resistor R4?

A: 1.5 A

B: 2 A

C: 4 A

D: 6 A

E: 12 A


(Circuits-08)

A circuit is built with two different resistors in series, as shown.

I) What can you say about the current flowing past points A and C?

A: IA = IC

B: IA > IC

C: IA < IC

D: Not enough info.

II) What can you say about the voltage drop across resistor R1 (i.e. VA-VB), compared to the voltage drop across resistor R2 ( i.e. VB-VC)

A: (VA-VB) = (VB-VC ) = 5 V

B: (VA-VB) = (VB-VC ) = 2.5 V

C: (VA-VB) > (VB-VC)

D: (VA-VB) < (VB-VC)

E: Not enough info.


(Circuits-09)

A circuit is built with two resistors in parallel, as shown.

I) What can you say about the current flowing past points A and B?

A: IA = IB

B: IA > IB

C: IA < IB

D: Not enough info.

II) What can you say about the voltage drop across resistor R1 (i.e. VA-VC), compared to the voltage drop across resistor R2 ( i.e. VB-VD)

A: (VA-VC) = (VB-VD ) = 5 V

B: (VA-VC) = (VB-VD ) = 2.5 V

C: (VA-VC) > (VB-VD)

D: (VA-VC) < (VB-VD)

E: Not enough info.