Cell having an emf E and internal resistance r is connected across a variable external resistance R. As the resistance R is increased, the plot of potential difference V across R is given by:
The potential difference across the external resistance R is given by:
V = E (R / (R + r)).
As R increases, the voltage V approaches E asymptotically. Initially, when R is small, a significant voltage drop occurs across the internal resistance r. As R increases, more of the emf is available across R, but it never exceeds E. This behavior corresponds to the graph shown in option (c), which correctly represents the relationship between V and R.
Thus, the correct answer is (c).
Important Questions from Current Electricity
Figure shows drift speed Vd of conduction electrons in a copper wire versus position (X) for the three sections. Then,
A. Radius of III > Radius of II > Radius of I
B. Electric Field in III > Electric Field in II > Electric Field in I
C. Radius of wire is same in all sections
D. Conductivity is same in all sections
Choose the correct answer from the options given below:
Which of the following circuits cannot be used to measure the resistance of resistor R?
The temperature at which the resistance of a conductor becomes 30% more than that of its resistance at 47°C will be:
(Given the value of the temperature coefficient of resistance of the conductor is 2 × 10-4 K-1.)
In the potentiometer circuit, the balance point is at X. The balance point will be shifted right towards B when:
A. Resistance R is increased keeping all other parameters constant
B. Resistance S is increased keeping all other parameters constant
C. Cell P is replaced by another cell whose emf is lower than Q
D. The polarity of Q is reversed
Choose the correct answer from the options given below:
Kirchhoff’s First Law, ∑ I = 0 at a junction deals with conservation of:
