हिंदी
CBSESecondary School (English Medium) (5 to 8) Class 7
पाठ्यपुस्तक उत्तर८८४८
अवधारणा स्पष्टीकरण और वीडियो२४९
पाठ्यक्रम

Heating Effect of Electric Current

Advertisements

Topics

Maharashtra State Board: Class 10

Introduction

The heating effect of electric current refers to the generation of heat when an electric current flows through a conductor. This effect is widely used in various devices and appliances, such as electric heaters, bulbs, and irons, to perform useful tasks.

How it Works:

When an electric current passes through a conductor (like a wire), the electrons collide with the atoms of the conductor. This collision causes the atoms to vibrate, which generates heat. The amount of heat produced depends on the current, the resistance of the conductor, and the duration of current flow.

Maharashtra State Board: Class 10

Joule’s Law of Heating

Joule’s Law explains the relationship between the heat produced and the factors involved. The law states that the amount of heat produced (H) is directly proportional to

  • The square of the current (I²)
  • The resistance of the conductor (R)
  • The time (t) the current flows.

Mathematically, this is expressed as : H = I²Rt

Where:

  • H = Heat produced (in Joules)
  • I = Electric current (in Amperes)
  • R = Resistance of the conductor (in Ohms)
  • t = Time (in seconds)
Maharashtra State Board: Class 10

Applications:

  1. Electric Bulbs: In an electric bulb, a tungsten filament is used. When current flows through the filament, it gets heated to a high temperature (up to 3400°C), emitting both light and heat. The heating effect of the current in the filament is what makes the bulb glow.
  2. Electric Heaters: Electric heaters make use of the heating effect by passing current through a resistive coil (usually made of Nichrome). This coil heats up and is used to heat water or air.
  3. Electric Irons: The heating element in an electric iron is designed to get hot when the current passes through it. This heat is used to press clothes.
  4. Toasters and Electric Cookers: Similar to electric heaters, these appliances use coils with high resistance. The current passing through these coils generates heat, which is used for cooking or heating food.

Uses of coil

Maharashtra State Board: Class 10

Units of Power and Energy

The electric power is measured in watts (W), where 1 W is a small unit. In practice, we often use kilowatts (kW) to measure power.

  • 1 kW = 1000 W
  • If 1 kW of power is used for 1 hour, it will consume 1 kWh of energy, which is equal to:
    • 1 kWh = 1 kW × 1 hr = 1000 W × 3600 s = 3.6 × 10⁶ J (Joules)
Maharashtra State Board: Class 10

Safety Measures and Overloading:

The heating effect of electric current can be dangerous if the current exceeds safe limits. Overloading a circuit or a device can cause the wires or equipment to overheat, leading to fire hazards or damage to the electrical components.

  • Short Circuits: A short circuit occurs when the live and neutral wires touch, causing a large current to flow, generating excessive heat. This can cause fires if inflammable materials are nearby.
  • Fuse Wire: To prevent damage from excessive current, a fuse wire is used in electrical circuits. If the current exceeds the safe limit, the fuse wire melts and breaks the circuit, stopping the current flow and preventing further damage or fire.

  • Miniature Circuit Breakers (MCBs): In modern electrical systems, MCBs are used instead of fuse wires. They automatically cut off the current if it exceeds the safe limit, providing better protection against overheating and overloading.

Overloading and Power Surges:

Overloading occurs when too many electrical devices are used at once, drawing excessive current from the transformer. If the transformer cannot handle the load, the fuse in the transformer melts, shutting down the supply to prevent damage.

Maharashtra State Board: Class 10

Definition: Heating effect of electric current

When a resistor is connected in an electrical circuit, heat is produced in it due to the current. This is known as the heating effect of current.

CBSE: Class 10
Maharashtra State Board: Class 10

Key Points: Heating Effect of Electric Current

  • Heating Effect: Current through a resistor produces heat, calculated by H = I²Rt or H = VIt (Joule’s Law).
  • Heat Applications: Used in devices like irons, heaters, bulbs, and fuses (to stop excess current).
  • Power Unit: 1 kWh = 3.6 × 10⁶ J, called 1 unit of electrical energy in electricity bills.
  • Short Circuit & Fuse: A short circuit causes a large current; the fuse wire melts to break the circuit and prevent fire.
  • MCBs: Miniature Circuit Breakers automatically cut off power during overload or fault conditions.

Shaalaa.com | Electricity part 11 (Heating effect of current)

Shaalaa.com


Next video


Shaalaa.com


Electricity part 11 (Heating effect of current) [00:09:15]
S
Series: series 1
0%


Electricity part 11 (Heating effect of current)
00:09:15  undefined

Related QuestionsVIEW ALL [151]

Solve the following example.

Two tungsten bulbs of wattage 100 W and 60 W power work on 220 V potential difference. If they are connected in parallel, how much current will flow in the main conductor? 

The current passing through an electric kettle has been doubled. The heat produced will become:

(a) half
(b) double
(c) four time
(d) one-fourth 

An electric component used as a safety device is electric circuit is ______.

State four most common electrical appliances based on heating effect of electric current. Why do we use finely heated platinum wire in surgery?

An electric iron of resistance 20 ohms draws a current of 5 amperes. Calculate the heat produced in 30 seconds.

What is the heating effect of electric current?

An electric iron is connected to the mains power supply of 220 V. When the electric iron is adjusted at ‘minimum heating' it consumes a power of 360 W but at 'maximum heating’ it takes a power of 840 W. Calculate the current and resistance in each case.

Define the following:

Electrolyte

Advertisements
Share
Notifications

Englishहिंदीमराठी
Login
Create free account


      Forgot password?
Course
Use app×