Unit 7 Current Electricity Review

What is an electric current?

• a build up of electrons

• the difference in charge between 2 points

• the flow of electrons over a circuit

• the opposition to flow of electrons

Unit of charge in SI unit is.....

• Coulomb C

• Resistivity ρ

• Ampere A

• Potential difference V

SI unit of electric current is ..

• watt

• ampere

• volt

• jule

The symbol used to express the current is......

• V

• I

• R

• C

What specifically does resistance reduce the flow of?

• Current

• Voltage

• Electricity

Answer explanation

Resistance specifically reduces the flow of current.

Which of these correctly shows Ohm's law?

• V = IR

• V = I ÷ R

• V = CR

Answer explanation

V = IR does correctly show Ohm's law. Voltage equals current multiplied by resistance.

If a current of 10 amperes flows through a 230 volt lamp, what is its resistance?

• 2300 ohms

• 23 ohms

• 23 ohms

Which of these equations is used to calculate current?

• C = Q × t

• C = Q ÷ t

• I = Q ÷ t

Answer explanation

Current is calculated by Q ÷ t where Q is charge and t is time.

What is the current if a charge of 25 coulombs passes in 5 seconds?

• 0.2 Amps

• 125 Amps

• 5 Amps

What is the following component?

• dry cell
• fuse
• battery
• resistor