Concepts Of Physics MCQ Edition [Volume 2]PhysicsElectric Current in Conductors
A battery with an emf of 100 V and a resistor having a resistance of 10 k are connected in series. This arrangement serves as a source to deliver current to an external resistance R . Provided that R does not exceed 100 , the current flowing through it remains constant up to two significant digits. Determine the value of this current. (This illustrates the fundamental principle of a constant-current source.)
Options
- A0.001 A
- B1 A
- C0.1 A
- D0.01 A
Correct answer
D. 0.01 A
Step-by-step solution
The total resistance of the circuit is R_ eq = 10 k + R = 10000 + R . Since R 100 , we have R 10000 . Therefore, the equivalent resistance is approximately R_ eq 10000 . The current flowing through the external resistance is given by Ohm's law: I = E R_ eq 100 10000 = 0.01 A This current remains approximately constant for small values of R , acting as a constant-current source.