10 Electrical Ciruits

Question 1

Kirchhoff’ s first law

Answer 1

Current into a junction = current out

Question 2

Kichhoff’s second law

Answer 2

In an circuit the sum of the electromotive force is equal to the sum of the potential differences around a closed loop

Question 3

Kirchhoff’s laws in series

Answer 3

The current is the same in every component
Potential difference is shared proportionally between components based on resistance big R -> big V

Question 4

Kirchhoff’s laws in parallel

Answer 4

Current is shared proportionally between components based on resistance big R -> small I
EMF is equal to the potential difference in each component

Question 5

Rt in series

Answer 5

R1 + R2+ …

Question 6

Vt in series

Answer 6

V1 + V2 + …

Question 7

Rt in parallel

Answer 7

1/Rt = 1/R1 + 1/R2 + …

Question 8

It in parallel

Answer 8

I1 + I2 + …

Question 9

What are the four important equations for analysing circuits

Answer 9

Q = It
W = VQ
P = IV
V = IR

Question 10

Lost volts = Epsilon - V

Answer 10

Lost volts = EMF - terminal pd

Question 11

How does current effect lost volts

Answer 11

As current increases lost volts increases as current decreases lost volts decreases

Question 12

Lost volts = Ir

Answer 12

Lost volts = current x internal resistance

Question 13

Epsilon = I(R + r)

Answer 13

EMF = current ( resistance + internal resistance)

Question 14

How can varying potential difference be achieved

Answer 14

Using a potential divider and a variable resistor

Question 15

Potentiometer

Answer 15

A variable resistor with three terminals and a sliding contact. Used in low voltage electrical circuits