Q4 of 11 Page 44

The following table shows current in Amperes and potential difference in Volts.

A. Find the average resistance.


B. What will be the nature of the graph between the current and potential difference? (Do not draw a graph.)


C. Which law will the graph prove?


A. According to the equation V = IR


R = V/I


Resistance in the 1st case R1 = V1/I1


= 4/9


= 0.444 Ω


Resistance in the 2nd case R2 = V2/I2


= 5/11.25


= 0.444 Ω


Resistance in the 3rd case R3 = V3/I3


= 6/13.5


= 0.444 Ω


Average resistance Ravg =


= (0.444 + 0.444 + 0444)/3


= 0.444 Ω


B. In this case as R is constant, we can observe the increase in I as V increases.


We know that V = IR .


It represents a straight line starting from origin with a slope R. Therefore, the nature of graph between current and potential difference will be a straight line.


The graph is given below:



C. The graph proves Ohm's law.


According to Ohm's law the current passing through a conductor between two points is directly proportional to the voltage across the two points.


IV


I = V/R


More from this chapter

All 11 →
2

The following figure shows the symbols for components used in the accompanying electrical circuit. Place them at proper places and complete the circuit.


Which law can you prove with the help of the above circuit?

3

Umesh has two bulbs having resistances of and He wants to connect them in a circuit, but if he connects them one at a time the filament gets burnt. Answer the following.

A. Which method should he use to connect the bulbs?


B. What are the characteristics of this way of connecting the bulbs depending on the answer of A above?


C. What will be the effective resistance in the above circuit?

5

Match the pairs

6

The resistance of a conductor of length x is r. If its area of cross section is a, what is its resistivity? What is its unit?