Current Voltage Power

​Current Electricity

​Chethana Amarasinghe

​Atomic Structure

​•Nucleus contains Protons and Neutrons.

•Protons have a positive charge.

•Nucleus is positively charged because it contains protons.

•Electrons are orbiting around the nucleus.

•Electrons are negatively charged

•An atom is neutral because it has equal number of protons and electrons.

Multiple Choice

These are the particles in the nucleus of an atom.

• Electrons & Protons

• Neutrons and Protons

• Electrons and Neutrons

• Positrons and Neutrons

Multiple Choice

This subatomic particle is negatively charged.

• Electron

• Proton

• Neutron

• Nucleus

​Positive ions and Negative ions

​When electrons are removed from the atom, it becomes positively charged.

​When an atom gains electrons, it becomes negatively charged.

​Charges

​Battery

​•At the negative terminal of the battery electrons get released due to a chemical reaction.

•At the positive terminal positive ions get created due to a chemical reaction.

​What is happening inside a Battery?

​Recharging a rechargeable battery..

​How do electrons flow?

​•Conductors have free electrons in them.

•If a battery is not connected, they move in random directions.

•When a battery is connected, battery pushes the electrons to one direction.

​​How do electrons flow?

​Charge and Current

​•Electrons are negatively charged particles and they carry energy from the battery through wires as electricity.

•Charge is measured in Coulombs (C).

•Electrons are so small and has a very small charge.

​Charge of an electron

​​Electric Current

​Electrical current is defined as the rate of flow of charges (electrons) through a conductor.

Multiple Choice

Unit of Charge is,

• Amperes

• Electrons

• Coulombs

• Volts

Multiple Choice

Unit of Current is,

• Coulombs

• Volts

• Watts

• Amperes

Multiple Choice

How much charge has moved if a current of 13 A flows for 10 s?

• 1.3 C

• 130 C

• 0.77 C

• 13 C

Multiple Choice

How much current flows when 10 C passes down a wire in 2 s?

• 5 A

• 0.2 A

• 20 A

• 10 A

Multiple Choice

A current of 1.5 A flows through a simple electrical circuit. How many coulombs of charge flow through a point in 60 seconds?

• 90 C

• 0.025 C

• 40 C

• 45 C

Multiple Choice

There is a current of 0.5 A through a light bulb. How much charge passes through the bulb in 4 hours?

• 2 C

• 28 800

• 120 C

• 7200 C

Multiple Choice

How long does it take for 64 C charge to pass through a cross-sectional area of a wire that carries a current of 72 A?

• 0.89 s

• 1.125 s

• 64 s

• 0.72 s

​DC and AC Current

​Direct Current

In a direct current, the flow of electrons is consistently in one direction around the circuit

Alternating Current

In an alternating current, the direction of electron flow continually reverses.

​Mains electricity gives Alternating current.

A cell or a battery gives Direct current.

​Measuring current

​Voltage (V)

​Cells or batteries move charges around circuits by transferring energy to the charges.

​The amount of energy given to 1 C of charge is known as the voltage.

Unit of voltage= Volts (V)

​A 6 V battery gives 6 J of energy to each Coulomb of charge that passes through the battery.

A 9 V battery gives 9 J of energy to each Coulomb of charge that passes through the battery.

Voltage is also known as potential difference.

Multiple Choice

What is the unit of Energy?

• Watts

• Joules

• Volts

• Coulombs

Multiple Choice

What is the potential difference between two points if 2 C of charge shifts 4 J?

• 0.5 V

• 8 V

• 2 V

• 4 V

Multiple Choice

How much energy is transferred when 3 C of charge moves through a potential difference of 6 V?

• 3 J

• 0.5 J

• 2 J

• 18 J

​Electric Power

​One watt is the power when one joule of energy is transferred in one second.

1 W=1 J/s

​​Power is the amount of energy transferred per second.

Power is measured in Watts (W).

​Can you build up the connection ?

Multiple Choice

What is the power rating of an electric heater that draws a current of 12.5 A when plugged into the mains supply of 230 V?

• 2875 W

• 1840 W

• 4650 W

• 230 W

Open Ended

The electric power consumed by a circuit with one light bulb is 3 W. The voltage of the battery is 3 V. What is the current in the circuit?

Open Ended

The electric power consumed by a circuit with one light bulb is 6 W. The current in the circuit is 4 A. What is the voltage of the circuit?