Pg:- 108,109
Ch:- 6
Energy transfer in an electrical circuit occurs when electrical energy is converted into other forms of energy, such as heat, light, or mechanical energy.
Components of Energy Transfer in a Circuit:
Energy Source:
The energy source, such as a battery or generator, provides electrical energy.
In a battery, chemical energy is converted into electrical energy.
In a generator, mechanical energy is converted into electrical energy.
Electric Current:
Electric current is the flow of electric charge (usually electrons) through the circuit.
Current carries energy from the source to other components in the circuit.
Circuit Components:
Resistors: Convert electrical energy into heat (e.g., in a heater).
Light Bulbs: Convert electrical energy into light and heat.
Motors: Convert electrical energy into mechanical energy.
Capacitors and Inductors: Temporarily store energy and release it later.
Mechanism of Energy Transfer:
Potential Difference (Voltage):
The source creates a potential difference across the circuit, providing the "push" that moves charges.
Voltage represents the energy transferred per unit charge.
Work Done on Charges:
Charges gain energy as they pass through the source and lose energy as they pass through resistive components or perform work.
Power in the Circuit:
Power (P) is the rate at which energy is transferred.
It is calculated as: P=IV Where I is current and V is voltage.
Power can also be expressed in terms of resistance (R) as: P=I^2 R
Energy Conservation in Circuits:
Energy is conserved in a closed circuit.
The electrical energy supplied by the source is equal to the total energy converted by the components.
If E is the total energy supplied by the source: E= ∑ Energy dissipated by components (e.g., resistors, light bulbs, etc.)..
Example:
In a simple circuit with a battery and a resistor:
The battery provides energy by creating a potential difference.
Electrons flow through the circuit, transferring energy to the resistor.
The resistor converts electrical energy into heat (or light in some cases).
1. Explain the energy conversion that occurs in a circuit containing a battery, a resistor, and a light bulb.
2. If a 12V battery powers a 6-ohm resistor, calculate the power dissipated in the resistor.
3. A motor in a circuit converts electrical energy into mechanical energy. Describe how the principles of energy conservation apply to this circuit.
4. Compare the roles of capacitors and resistors in energy transfer within a circuit.
5. In a circuit with two resistors (4 ohms and 8 ohms) in series connected to a 24V battery, calculate the power dissipated in each resistor.
6. Describe how potential difference (voltage) influences energy transfer in an electric circuit.
7. If a circuit has a 1.5A current flowing through a 10V battery, calculate the power of the energy source. What does this power represent in terms of energy transfer?