# How the resistance of a single lamp changes with the potential difference across the lamp?

Contents

As the potential difference across the filament lamp increases the current across the lamp also increases due to Ohm’s law. The increase in current flow also causes the lamp to heat up which causes the resistance of the lamp to also increase.

## Why does the resistance of the lamp increase as the potential difference across the lamp increases?

The more energy that is put into the bulb, the harder it is for the current to flow – the resistance of the bulb increases. As the potential difference increases, so does the temperature of the thin wire inside the bulb, the filament.

## Why does the resistance of a lamp change?

The resistance of a lamp increases as the temperature of its filament increases. The current flowing through a filament lamp is not directly proportional to the voltage across it.

## What happens when potential difference across a resistance increases?

Electric potential would increase when resistance increases given a constant current. Voltage would have to be higher to maintain the same current when resistance is higher.

## Why does the resistance of a filament lamp change with voltage?

The resistance of a filament lamp increases as the potential difference increases because the filament becomes hot. The movement of electrons (which is what causes the current) makes the atoms inside the filament vibrate faster and this makes the filament heat up.

## Why doesn’t a filament lamp obey Ohm’s law?

The tungsten filament in the bulb does not follow Ohm’s law. As the voltage in the wire filament increases it heats up. The resistance of a wire changes as its temperature changes. … Often if extreme currents are applied to wires, they heat up, change their resistances, and violate Ohm’s law.

## Why do filament lamps have high resistance?

This is because the filament gets hot, which causes the resistance to increase. At high temperatures, the atoms in the filament vibrate more. The electrons in the current now collide more with the atoms. … As the potential difference increases, the current no longer increases as much.

## How do you find the resistance of a lamp?

Calculating resistance

1. To find the resistance of a component, you need to measure:
2. The resistance is the ratio of potential difference to current. …
3. For example, 3 A flows through a 240 V lamp. …
4. resistance = 240 ÷ 3 = 80 Ω
5. If you plot a graph of current against potential difference for a wire, you get a straight line.

## Do you expect the resistance of a light bulb to remain constant?

A light bulb is a simple example; the filament undergoes huge changes in temperature when current passes through it. Therefore, the resistance of the filament is not constant, rather, it increases with increased current.

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## Is potential difference directly proportional to resistance?

Ohm’s Law as a Predictor of Current

The current in a circuit is directly proportional to the electric potential difference impressed across its ends and inversely proportional to the total resistance offered by the external circuit. … And the greater the resistance, the less the current.

## What is the potential difference across the 4 ohm resistor?

Voltage across 4Ω resistance =IR=1×4=4V.

## Does resistance affect voltage?

First way a resistor reduces voltage : Voltage drop across its terminals. In the field of electronics, voltage drop occurs in every component that has a resistance. … Since we know the voltage and resistance values, we can calculate the current using ohm’s law (I = V/R) which gives us a current of 1.2 amps.

## Does a filament lamp obey Ohm’s law?

If a component is ohmic (it obeys Ohm’s Law), then its resistance must be independent of current and voltage. … An example of this is the filament light bulb, in which the temperature rises as the current is increased. Here, Ohm’s law cannot be applied.

## Why does resistance increase with voltage?

Resistance doesn’t increase directly because of Voltage. Increasing the voltage for a circuit with a given resistance increases the current flow. The electrical resistance of a circuit component or device is defined as the ratio of the voltage applied to the electric current which flows through it. 