Free Printable Science & Principles RA04

1.

What is the conventional flow of current?

a)

From negative to positive in an open circuit

b)

From negative to positive in a closed circuit

c)

From positive to negative in an open circuit

d)

From positive to negative in a closed circuit

2.

Which of the following electrical terms is correct?

a)

The symbol for Impedance is Z and it is measured in Amperes

b)

The symbol for Impedance is X and it is measured in Ohms

c)

The symbol for Impedance is Z and it is measured in Ohms

d)

Impedance, which has a symbol A, is measured in Amperes

3.

What is the formula to calculate Impedance?

a)

Z = R²+ X²

b)

$Z\ =\ \sqrt[]{R^2\ -\ X^2}$

c)

$Z\ =\ \sqrt[]{R^2\ +\ X^2}$

d)

$Z\ =\ \sqrt[]{X^2\ +\ Y^2}$

4.

If $\frac{Np}{Ns}=\frac{Vp}{Vs}=\frac{Is}{Ip}$ , which of the following would correctly calculate the number of primary turns for a transformer?

a)

$Ns\ =\ \frac{Is}{Ip}\times\frac{Vs}{Vp}$

b)

$Np\ =\frac{Vp\times Ns}{Vs}$

c)

$Np\ =\ \frac{Is\ \times Np}{Ip}$

d)

$Ns\ =\ \frac{Np}{Ns}$

5.

Which of the following would be the correct value for 72,000,000 watts?

a)

72 Giga watts

b)

72 kilo watts

c)

72 milli watts

d)

72 Mega Watts

6.

Which of the following values would represent 36μΩ?

a)

0.00036Ω

b)

0.0036Ω

c)

0.000036Ω

d)

$3.6\ \times10^{-3}$

7.

What is the current flowing in a circuit when a voltage of 230V is applied and two resistors of 28.75Ω each are connected in series?

a)

8 Amperes

b)

4 Amperes

c)

0.125 Amperes

d)

0.25 Amperes

8.

What is the power dissipated when two 23Ω resistors are connected in parallel across a 230 volt supply?

a)

4.6 kW

b)

460 W

c)

46000 W

d)

2.3 kW

9.

What is the potential difference across each of the four 20 Ω resistors when they are connected in parallel to a 230V supply?

a)

11.5 V

b)

11.5 A

c)

230 V

d)

230 A

10.

What is the value of a resistor connected in series with two other resistors of 2.6Ω and 3.8Ω that gives a total resistance of 25Ω

a)

18.6Ω

b)

3.2Ω

c)

11.55Ω

d)

5.8Ω

11.

Two resistors of 2.6Ω and 3.8Ω are connected in parallel. What would be the value of a third resistor, that when connected in parallel with the first two would provide a total combined resistance of 1.2Ω

a)

5.4Ω

b)

7.6Ω

c)

1.2Ω

d)

0.9Ω

12.

The voltage drop of a cable carrying 12 amperes is 3.6 volts. Calculate the power wasted in the cable.

a)

15.6 W

b)

8.4 W

c)

0.3 W

d)

43.2 W

13.

A copper cable with a resistance of 36mΩ has 24 Amperes drawn through it for a 5.52 kW load. Calculate the power wastage in the cable.

a)

0.864 watts

b)

230 watts

c)

20.74 watts

d)

230 volts

14.

If the area of a cable is doubled and the length is halved, what would happen to the total resistance?

a)

Doubles in value

b)

Halves in value

c)

Four times the value

d)

Quarter of the value

15.

The resistance of a 6 mm² copper cable, with a resistivity of 17.2 × $10^{-9}$ , is 0.166Ω. What is the length of the cable?

a)

5.8 meters

b)

58 meters

c)

5.8 x $10^2$ meters

d)

$0.58\ \times10^{-3}\ meters$

16.

Which of these 100m copper cables has a resistance of 3.44Ω if the resistivity is $17.2\ \times10^{-9}$ ?

a)

1 mm²

b)

1.5 mm²

c)

2.5 mm²

d)

4 mm²

17.

Which of these meters is connected both in series and in parallel to the load?

a)

Ohm meter

b)

Volt meter

c)

Watt meter

d)

Ampere meter

18.

Which of these devices uses an electromagnet to control the flow of fluid?

a)

Transformer

b)

Solenoid valve

c)

Diverter valve

d)

Motor

19.

A conductor carrying 20 Amperes and 20 meters long is situated in a $0.2\frac{Wb}{m^2}$ magnetic field.

What is the force exerted on that conductor?

a)

2000 N

b)

42 N

c)

80 N

d)

8 N

20.

The EMF produced by a 25 cm cable passing through a 1.1 T magnetic field at 5 M/s is...

a)

0.055 V

b)

2 V

c)

1.1 V

d)

1.375 V

21.

What is the peak value of a sine wave if the RMS value is 70.7V?

a)

141.4 V

b)

111.16 V

c)

100 V

d)

49.99 V

22.

What is the frequency produced by a 10-pole generator rotating at 15000 revolutions per minute?

a)

1500 Hz

b)

50 Hz

c)

25 Hz

d)

1.25 kHz

23.

Calculate the mass of a body that has a weight of 1049.67 N.

a)

107 kg

b)

107 N

c)

9.81 kg

d)

9.81 N

24.

A motor that has an input of 1.25 KW is 85% efficient. What is the output power?

a)

106.25 W

b)

1470.59 W

c)

1.0625 MW

d)

1.0625 $\times10^3\ W$

25.

What is the force exerted on a load when it is moved for 20 meters, if the work done is 7,000 Nm?

a)

7,020 N

b)

140,000 N

c)

350 N

d)

6,800 N

26.

A pair of scissors is which class of lever?

a)

Class 4 lever

b)

Class 3 lever

c)

Class 2 lever

d)

Class 1 lever

27.

What type of lever has the effort and fulcrum at each end?

a)

Class 1

b)

Class 2

c)

Class 3

d)

Class 4

28.

The effort on a three-pulley system is used to lift a 900 N motor 30 cm from its base. How much effort and distance must be made on the rope to achieve this?

a)

300 N and 0.9 M

b)

90 cm and 300 N

c)

900 N and 30 cm

d)

300 N and 30 cm

29.

What is a thermistor used for?

a)

Sensing resistance to control temperature

b)

Sensing temperature to control resistance

c)

Sensing temperature for control purposes

d)

Sensing resistance for control purposes

30.

A motor gear with a diameter of 25.5 cm has 4 teeth per cm on its circumference. If it is driving a load gear with 80 teeth, approximately how many rotations must the driven gear make to complete two rotations of the driver gear?

a)

4

b)

8

c)

2

d)

3

31.

Which of the following statements is accurate for a step-down transformer?

a)

The number of primary and secondary turns are equal.

b)

The current is higher on the secondary winding.

c)

The current is equal on both the primary and secondary coils.

d)

The current is higher in the primary coil.

Science & Principles RA04

Total questions: 31

Worksheet time: 49mins

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