Resistance, R, is defined by Ohm’s Law as the ratio of potential difference (vol

Question

Resistance, R, is defined by Ohm’s Law as the ratio of potential difference (voltage) to electric current. A resistor is an electric component which has a constant resistance independent of the voltage applied or current flowing.

A student sets up a circuit to investigate the behavior of resistors. She uses a variable power supply as illustrated in Figure 1.

Figure 1

The student first conducts a series of experiments measuring power and current as the voltage is varied. The results are shown in Figures 2 and 3.

In another experiment, the student connects five resistors in to a 10 V battery as shown in Figure 4.

Figure 4

15. What is the meaning of the slope of Figure 2?

A) Resistance

B) Reciprocal of resistance

C) Power

D) Current

E) Energy

16. What is the meaning of the slope of Figure 3?

A) Resistance

B) Reciprocal of resistance

C) Power

D) Current

E) Energy

17. In Figure 4, how does the current in the 6 ohm resistor, I6, compare to the current in the 12 ohm resistor, I12?

A) I6 is half of I12

B) I6 is twice of I12

C) I6 is equal to I12

D) Not enough information to tell.

18. In Figure 4, how does the current in the 16 ohm resistor, I16, compare to the current in the 12 ohm resistor, I12?

A) I16 is three-quarters of I12

B) I16 is one-third of I12

C) I16 is equal to I12

D) I16 is three times of I12

19. What is the current in the 10 ohm resistor of Figure 4?

A) 1.0 A

B) 0.50 A

C) 0.25 A

D) 0.16 A

E) 0.33 A

20. If the student replaces the 12 ohm resistor with a smaller value, which of the following is true?

A) The voltage across the 20 ohm resistor will increase

B) The voltage across the 20 ohm resistor will decrease

C) The current in the 10 ohm resistor will decrease

D) The power delivered by the battery will decrease

E) The voltage across the battery will increase

Explanation / Answer

15) fig 2 is a graph b/w power and voltage and it is straight line

so P = m v , where m is slope

as we know P = I × V

compare both eqution we will get m= I

so slope of fig 2 is --

D)current

16) fir 3 is a graph b/w I and V

so by graph we can write I =mV

so m= I/V

and by ohm's low V= I R

R = V/I

so by both equtions

m = 1/R

so slope of fig 3 is

B) Reciprocal of resistance

17)

in fig 4 the Req = 20 ohm

and V= 10

so I =1/2 amp

by current distribution as we know in parallel circuit current diveded in opposite ration of resistance .

current in 12 ohm is = (1/4 ) * 6/18

current in 6 ohm is = (1/4) * 12/18

so ( B) I6 is twice of I12

18) by previous ans I12 = o.0833 amp

and I6 =0.1666 amp

and we know that I16 = I6 + I12 = o.2499 amp

so D) I16 is three times of I12

19) current in 10 ohm = 10/20 = 0.5 amp

B) 0.50 A

20) if resistance 12 ohm will reduce then current in 20 ohm willl decrese so volatge across it will reduce

so B) The voltage across the 20 ohm resistor will decrease

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