Principles of basic electrical circuits

Which of the following formulas can calculate power in a resistive circuit

3 x 12Ω resistors are connected in parallel to a 200V supply, calculate the total power of the circuit.

• 10,000W

• 400W

• 1,000W

• 1,111W

Two resistors of 20 ohms and 40 ohms are connected in series across a 120v d.c. supply, the current flowing in the circuit will be:

• 20 A

• 2 A

• 5 A

• 0.5 A

If three resistors are connected in series and have resistances of 20 Ω, 30 Ω, and 40 Ω then the total resistance would be

• 100 Ω

• 90 Ω

• 70 Ω

• 80 Ω

3 x 20Ω resistors are connected in series to a 200V supply, calculate the total power of the circuit.

• 10 KW

• 0.666 KW

• 0.333 KW

• 12 KW

To measure the current through a load the meter must be connected

• across the load

• in parallel with the supply

• in parallel with the load

• In series with the load

To measure the voltage across a load the meter must be connected

• before the load

• in parallel with the supply

• in parallel with the load

• In series with the load

If four resistors each of 50 Ω are connected in parallel the overall resistance is

• 25 Ω

• 100 Ω

• 12.5 Ω

• 200 Ω

When current flows in a conductor, a magnetic field is created around the conductor

• when the voltage is high enough

• only if it is a coil

• as long as the current flows

• only when d.c is applied

Of the following materials which would be the BEST conductor of electricity?

• Nichrome

• Steel

• Aluminium

• Copper

A poor conductor of electricity is:

• Glass

• Copper

• Aluminium

• Silver

The resistance of an electrical conductor is:

• Affected by the weather

• Determined by the formula I = P x V

• Inversely proportional to length and proportional to c.s.a

• Proportional to the length and inversely proportional to the c.s.a

What is the formula for two resistors in parallel?

• R1 + R2/R1 - R2

• R1 - R2/R1 x R2

• R1 + R2/R1 x R2

• R1 x R2/R1 + R2

When the current through a conductor increases

• the voltage decreases

• the temperature decreases

• the temperature increases

• the resistance decreases

The current in a circuit is 100A and the resistance is 0.1 Ohm. The supply voltage is

• 14V

• 20V

• 12V

• 10V

The equation for current flowing in a resistive circuit is

• I = R/P

• I = R/V

• I = P/R

• I = V/R

The total resistance of two resistors of 20 Ohms and 35 Ohms connected in series is

• 50 Ohms

• 45 Ohms

• 15 Ohms

• 55 Ohms

When an electric current flows through a conductor it

• Cools down and expands

• Cools down and contracts

• Heats up and contracts

• Heats up and expands