Chapter 21, Problem 1CQ

To determine

The effect switch has on current when open and when closed.

Answer to Problem 1CQ

Switch open-low current, Switch close-high current.

Explanation of Solution

Given information:

The given statement is a switch has a variable resistance that is nearly zero when closed and extremely large when open, and it is placed in series with the device it controls.

The given figure is

  

Introduction:

Kirchhoff's second rule states that in a closed loop the sum of all the voltages is equal to zero.

Ohms law states that at constant temperature potential difference $V$ across the terminal is directly proportional to current $I$ flowing through the circuit

  $V=IR$

Where $R$ is a constant value known as resistance.

Equivalent resistance of several resistors connected in series is

  ${\text{R}}_{\text{eq}}{\text{=R}}_{\text{1}}{\text{+R}}_{\text{2}}\text{+}\mathrm{............}{\text{+R}}_{\text{N}}$

Resistance is the property which acts as a hindrance to the current which means it opposes the flow of current. It is given that a switch has a variable resistance that is nearly zero when closed.

The given figure has zero variable resistance which leads to larger current drawn from the circuit.

It is given that a switch has an extremely large variable resistance when open. In case of extremely large variable resistance the current will be very less because the large value of resistor opposes the flow of current.