Obtain the relation R 1 R 2 = R 3 R 4 for a Wheatstone’s bridge. The symbols have their standard meanings.

If the wheat stone bridge is balanced, No current in arm CD. So, Applying KVL in loop ACDA I 1 R 1 - I 2 R 3 = 0 ⇒ I 1 R 1 = I 2 R 3 . . . . . . . . . . . . . . . ( 1 ) Similarly Applying KVL in loop CBDC , I 1 R 2 - I 2 R 4 = 0 ⇒ I 1 R 2 = I 2 R 4 . . . . . . . . . . . . ( 2 ) Dividing (1) by (2) R 1 R 2 = R 3 R 4

E M B I B E

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 6 - DC Circuits and Measurements>QUESTIONS>Q 2

HARD

12th ICSE

IMPORTANT

Earn 100

Define the emf of a cell in terms of the work done in moving a charge through the cell. Using Joule’s law obtain the equation, $emf = I (R + r)$ .

Important Questions on DC Circuits and Measurements

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 6 - DC Circuits and Measurements>QUESTIONS>Q 3

Differentiate between emf and

PD

for a cell. Derive relationship between the two.

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 6 - DC Circuits and Measurements>QUESTIONS>Q 4

The figure below shows a cell of emf

E

and internal resistance

r

, connected to a voltmeter

V

and a variable resistance

R

. Deduce the relationship among

V, E, R

and

r

. How will

V

vary when

R

is reduced?
Question Image

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 6 - DC Circuits and Measurements>QUESTIONS>Q 5

When a battery of emf

E

and internal resistance

r

is connected to a resistance

R

, a current

I

flows through it. Derive a relation among

E, I, r

and R.

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 6 - DC Circuits and Measurements>QUESTIONS>Q 6

State and explain Kirchhoff's laws for electric circuits. What are the conservation laws implied in each law? State the sign convention for current and emf. Use the given circuit for your explanation.
Question Image