Physics help from experts.

## Physics Tutorials

### Ohm's Law, Heaters

Ohm's Law : Electric current passing through a conductor is directly proportional to the potential difference across it, when the temperature is constant. This constant of proportionality is the resistance of the conductor.

#### Explanation

For many electric conductors, the current flowing through them is directly proportional to the applied voltage. When we carefully observe OHM’S LAW, we see it depends upon the fact that the velocity of charges through the material is proportional to the electric field in the conductor. The ratio of voltage to current is called the resistance, and if the ratio is constant over a wide range of voltages, the material is said to be an "ohmic" material. If the material can be characterized by such a resistance, then the current can be predicted from the relationship:

E = IR

E = Voltage
I = Current
R = Resistance

Or

Volts = Amperes x Ohms

#### Application

A resistor is a part of a electrical circuit and is used to control the flow of electrical current and has specific resistance, which is measured in OHM’S . A heater consists of one or more electrically conductive foils connected to an electrical supply. The length of the circuit and the temperature determine the resistance of the conductor. Series heaters, are highly efficient resistive heating circuits. All of the heating effect is generated within a resistive metal core. Series resistance heating circuits are most often available for useful temperature applications up to 200°C and at power ratings up to 60W/m. They work when voltage is dropped across the electrical resistance, which is the series heater.

#### Question

How can Ohm's Law can be used to determine the amount of current I flowing in the circuit when voltage V is applied to resistance R. In the following circuit, assume that resistance R is 2 and voltage V that is applied to it is 12 V.

Answer: According to OHM’S LAW we know I=V/R

Therefore,

I = 12v / 2 Ohms

=6 Amperes of Current

more Ohm's Law problems

For help with physics problems, try Physics Homework Help

Mohit Ghai