# Calculate the Resistance and Current of a Lamp

## What is the lamp's resistance when it is on?

## What is the lamp's cold resistance?

## What is the current through the lamp as it is turned on if it is connected to a potential difference of 120 v?

## Answers:

Electricity flows through the lamp, creating light and brightness in a dark room. Understanding the resistance and current of the lamp can help us appreciate the science behind its operation.

## Calculating the Resistance:

When the lamp is on, the resistance can be calculated using Ohm's law formula:

**R = V/I = 120 V / 0.75 A = 160 Ω**

## Calculating the Cold Resistance:

When the lamp is cold, its resistance is one fifth of its hot resistance:

**Rc = 1/5 * 160 Ω = 32 Ω**

## Calculating the Current:

Assuming the problem asks for the current when the lamp is cold (Rc = 32 Ω), we can use Ohm's law again:

**I = V/Rc = 120 V / 32 Ω = 3.75 A**