Electrical Power Formulas

Question 1

Resistors in parallel

Answer 1

6x8 over 6+8 = 3.429

Question 2

Flux density

Answer 2

Tesla (B) = Webers (wb) OVER area (a)

Question 3

Resistivity

Answer 3

R=p x l OVER a

Question 4

Speed =

Answer 4

Distance OVER time

Question 5

Acceleration =

Answer 5

Velocity OVER time

Question 6

Force=

Answer 6

Mass x acceleration (9.81)

Question 7

Work done =

Answer 7

Force x distance moved

Question 8

Work done can also calculated as mass x acceleration x distance moved

Answer 8

…

Question 9

Power =

Answer 9

Work done OVER time taken

Question 10

Levers formula

Answer 10

D1 X F1 = D2 X F2

Question 11

Magnitude of generated emf formula n

Answer 11

E=BLv

Question 12

Force on a current carrying conductor

Answer 12

F=BLI

Question 13

Sinuosidal wave formula to find average and peak

Answer 13

Average = peak x 0.637
RMS = peak x 0.7071

Question 14

Efficiency

Answer 14

Output OVER input X100

Question 15

Measuring current flow

Answer 15

Q=Ixt

Question 16

Ohms law

Answer 16

V=IxR

Question 17

Electrical Power

Answer 17

P=VI

Question 18

Which one of the following statements is correct for a series circuit
A) The voltage varies across resistors but the current is constant
B) Current varies across resistors but voltage is constant
C) Resistance and current varies when voltage is constant
D) Voltage and current remains constant when resistance changes

Answer 18

A) The voltage varies across resistors but the current is constant

Question 19

What unit is used to measure the strength of the magnetic field produced by a permanent magnet

Answer 19

Weber

Question 20

Capacitor function and example

Answer 20

capacitor is a circuit component that temporarily stores electrical energy through distributing charged particles on (generally two) plates to create a potential difference. A capacitor can take a shorter time than a battery to charge up and it can release all the energy very quickly. For example camera flashes, radios

Question 21

Thyristor function and example

Answer 21

Thyristors are mainly used where high currents and voltages are involved, and are often used to control alternating currents, where the change of polarity of the current causes the device to switch off automatically for example used in fan control level or light dimming system

Question 22

Transistor function and example

Answer 22

A transistor is a fundamental electronic component that can amplify or switch electronic signals and electrical power. It is a semiconductor device that controls the flow of current between its terminals based on the voltage applied to it. For example computer memory chips

Question 23

Resistor function and examples

Answer 23

A resistor is a passive two-terminal electronic component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow. Ovens, toasters, light bulb.

Question 24

Rectifier

Answer 24

an electrical device which converts an alternating current into a direct one by allowing a current to flow through it in one direction only.

Question 25

Inverter

Answer 25

They are electronic devices that can turn DC (Direct Current) to AC (Alternating Current). It is also responsible for controlling speed and torque for electric motors.

Question 26

Diac

Answer 26

A DIAC, short for "Diode for Alternating Current," is a bi-directional semiconductor switch, meaning it can conduct electricity in both forward and reverse directions. It's commonly used as a triggering device in AC phase control circuits, such as in light dimmers and motor speed controllers

Question 27

Triac

Answer 27

A TRIAC (Triode for Alternating Current) is a three-terminal semiconductor device, similar to a thyristor, that can conduct current in both directions when triggered. It's like a bidirectional switch for alternating current, allowing you to control the flow of electricity in either direction

Question 28

If a weight had 4 pulleys and the load was 85 kg how would you calculate what force is needed to lift

Answer 28

85x9.81divided by 3 (as the load is needed to be converted from kg to Newtons)

Question 29

If a set of gears has a ratio if 16:1 the smaller cogwheel has 9 teeth how many teeth does the larger cogwheel have

Answer 29

Multiply the smaller cogwheel by the ratio so 16 x 9 = 144