This official sponsor may provide discounts for members

# Exam Questions

Discuss Exam Questions in the Electrical Courses and Electrical NVQ's area at ElectriciansForums.net

M

#### mikedunne101

Welcome to ElectriciansForums.net - The American Electrical Advice Forum

I have some sample questions im revising for my 2330 unit 1 exam. I was hoping somebody wouldnt mind explaining how to do them correctly!

20. 04 02 3
The current in a coil changes from 5A to 2A in 0.05seconds and induces a voltage of 30v in the coil the inductance of the coil is:

22. 04 04 5
A coil has an inductance of 0.1 H and is connected across a 50Hz a.c. supply, the value of inductive reactance of the coil will be:

18. The resistance of a 230v 3 kW immersion heater element will be

19. The force on a conductor 750mm long carrying a current of 6A placed at right angles in a field of 1.2 Tesla will be

21. A capacitor of 100µF is connected in parallel with a 20Ω pure resistor. The group is connected to a 200v 50Hz supply. Calculate the power dissipated in the combination.

sorry i know there is quite a few! any help would be appreciated, cheers.

K

#### kablue2000

19 is the formula F=BIL Force = Tesla *amp*length

#### Traineenoob

##### -
Hi are you doing the first year or second?? sounds like you revising for the unit 3 exam not unit 1

22.A coil has an inductance of 0.1 H and is connected across a 50Hz a.c. supply, the value of inductive reactance of the coil will be:

2 x 3.141 x 5o x 0.1 = 31.41 ohms

so it 2 x π x frequency x inductance
i think thats right anyway

Last edited:

#### john.irvine

##### -
18. The resistance of a 230v 3 kW immersion heater element will be

Power = volts squared devided by resistance

P=VxV
......R

3000=230X230
..............R
therefore
. 1 .= 1 R 1..
3000..230X230

therefore
R= 230 X230 =17.63ohms
........3000

Last edited:
S

#### staffok

formula is e=-L times change in current divided by change in time. Need to transpose. .-05x30 divided by 2-5= .5H. hope you understand that.

K

#### kiwisparks

Hi,go to the nz electrical workers registration board webb site,you will find all the questions and model answers for the electricalns theory papers,the regs paper & inspectors exam also available,not really relevant to uk, but has a few calculation examples as well.

good luck!

A

#### Andy Smith

Hi are you doing the first year or second?? sounds like you revising for the unit 3 exam not unit 1

22.A coil has an inductance of 0.1 H and is connected across a 50Hz a.c. supply, the value of inductive reactance of the coil will be:

2 x 3.141 x 5o x 0.1 = 31.41 ohms

so it 2 x π x frequency x inductance
i think thats right anyway

That’s Correct

XL = Inductive Reatance

XL = ωL = 2∏fL

21. A capacitor of 100µF is connected in parallel with a 20Ω pure resistor. The group is connected to a 200v 50Hz supply. Calculate the power dissipated in the combination

Xc = 1/ 2∏FC

= 1/2∏ x50x 100x10-6

= 31.831

Z = √ (R2 +Xc2) (this is R squared + Xc squared)

= 37.59 Ω

I = V /Z

= 200/ 37.59

= 5.32 A

Cos Ø = R/Z

= 20/37.59

= 0.53

PF = 57.99◦

P = V I Cos Ø

= 200 X5.32 X 0.53

= 563.92 W

20. 04 02 3
The current in a coil changes from 5A to 2A in 0.05seconds and induces a voltage of 30v in the coil the inductance of the coil is:

V = L x (di/dt)

30 = L x (3/0.05)

30 = L x 60

L = 30/60

= 0.5 H

= 500mH

Hope this helps been a while so double check please

Last edited by a moderator:
This official sponsor may provide discounts for members

Reply to Exam Questions in the Electrical Courses and Electrical NVQ's area at ElectriciansForums.net

This official sponsor may provide discounts for members
Courses and Training for:-