Electrical principles

What is ⅜ converted to a decimal?

• 0.375

• 2.67

• 0.725

• 0.4

13m of a 50m drum of cable is used. What is the percentage left on the drum?

• 26%

• 50%

• 74%

• 13%

 $R\ =\ \frac{pL}{A}$  

Make resistivity the subject of the formula, .

•  $p\ =\ \frac{RA}{L}$  

•  $R\ =\ \frac{AL}{p}$  

•  $R\ =\ \frac{pL}{A}$  

•  $p\ =\ \frac{L}{RA}$  

 $a^2\ =\ b^2\ =\ c^2$  

Rearrange the following formula to make ‘c’ the subject: 

•  $c\ =\ \sqrt{a^2\ -\ b^2}$  

•  $c\ =\ \sqrt{b^2\ -\ a^2}$  

•  $c\ =\ \sqrt{a^2\ +\ b^2}$  

•  $c\ =\ \sqrt{b^2\ +\ a^2}$  

How can 25kV be expressed in a different way?

• $25\ x\ 10^6$

• $25\ x\ 10^3$

• $25\ x\ 10^{-3}$

• $25\ x\ 10^{-6}$

How can 23mA can also be shown?

• $23\ x\ 10^3$

• $23\ x\ 10^6$

• $23\ x\ 10^{-3}$

• $23\ x\ 10^{-6}$

Four different meters are used to measure the resistance of a CPC.

What is the average reading if, individually they were: 1.3Ω, 1.05Ω,

1.24Ω, 1.12Ω?

• 1.18

• 1.2

• 4.71

• 1.51

An ohmmeter takes five readings on a circuit: 0.24Ω, 0.79Ω, 0.26Ω,

0.35Ω, 0.56Ω. What is the ‘range’ of the readings?

• 0.55

• 0.79

• 0.24

• 2.16

The SI unit m2 is used for what measurement?

• Volume

• Length

• Area

• Mass

What are the SI base units for volume and temperature?

• m3, °C

• m2, °K

• m2, °C

• m2, °K