Review MT 2 SH2

A generator produces a current of 40A, how long will it take for a total of 3000 C to flow through the output?

• 1 minutes

• 2 minutes

• 1 minutes and 30 seconds

• 1 minutes and 15 seconds

Calculate the energy gained by an electron when it is accelerated through a potential difference of 50 kV.

• 8.0 x 10^-15 J

• 1.6 x 10^-15 J

• 3.2 x 10^-15 J

• 4.0 x 10^-15 J

The current in an electric immersion heater in a school experiment is 6.3 A when the p.d across it is 12V. Calculate the resistance and the power of the heater.

• 1.9 Ω, 76 W

• 2.3 Ω, 96 W

• 2.5 Ω, 86 W

• 2.7 Ω, 106 W

Calculate the resistance per metre at room temperature of a constant wire of a diameter 1.25 mm. The resistivity of the wire at room temperature is 5.0 x 10^-7 Ω m.

• 0.32 Ωm^-1

• 0.56 Ωm^-1

• 0.41 Ωm^-1

• 0.73 Ωm^-1

When a cell is connected in series with a resistor of 2.0 Ω there is a current of 0.625 A. if a second resistor of 2.0 Ω is put in series with the first, the current falls to 0.341 A. Calculate the internal resistance of the cell and the e.m.f of the cell.

• 0.4 A, 1.5 V

• 0.3 A, 1.5 V

• 0.2 V, 3.0 V

• 0.5 A, 3.0 V

The current (I) in a copper wire can be calculated using the equation shown.

I = Anvq

What does the symbol v represent?

• The average drift velocity of the charge carriers

• The instantaneous velocity of the charge carriers

• The voltage applied across the wire

• The volume of the wire

Which values of current and resistance will produce a rate of energy transfer of 16 J s^–1?

• I = 1A, R= 4Ω

• I = 2A, R= 8Ω

• I = 4A, R= 1Ω

• I = 16A, R= 1Ω

Gold is sometimes used to make very small connecting wires in electronic circuits.

A particular gold wire has length 2.50 × 10^–3 m and cross-sectional area 6.25 × 10^–8 m². Gold has resistivity 2.30 × 10^–8 Ω m. What is the resistance of the wire?

• 3.6 × 10^–18 Ω

• 5.8 × 10^–13Ω

• 9.2 × 10^–4 Ω

• 6.8 × 10^–3 Ω

A wire of cross-sectional area 5.0 × 10^–6 m² is made of a metal of resistivity 50 × 10^–8 Ω m. The potential difference across the wire is 6.0 V and the current is 3.0 A.

What is the length of the wire?

• 0.050 m

• 0.20 m

• 5.0 m

• 20 m

A household electric lamp is rated as 240 V, 60 W. The filament of the lamp is made of tungsten from a wire of constant radius 6.0 x 10^-6 m. The resistivity of tungsten a normal operating temperature of the lamp is 7.9 x 10^-7 Ωm. For the lamp at its normal operating temperature, calculate the current in the lamp.

• 0.25 A

• 0.4 A

• 0.1 A

• 0.5 A