Internal resistance

Question 1

Internal resistance

Answer 1

When a power supply is part of a closed circuit, it must itself be a conductor. All conductors
have some resistance. A power supply has internal resistance, r.

Question 2

Terminal potential difference (Vtpd)

Answer 2

Energy available at the output of the supply - (when you measure across the supply)

Question 3

Lost volts

Answer 3

Voltage loses due to internal resistance.

Question 4

R

Answer 4

External resistance (like that of a resistor)

Question 5

E or E.m.f

Answer 5

Electromagnetic force - all the available energy from a power supply. Constant for a particular power supply.

Question 6

What happens with an increased current to the available energy in a power supply.

Answer 6

As current increases the more energy will be dissapated in the power supply until eventually all the available power is wasted and none available and none outside the power supply.

Question 7

Short circuit current

Answer 7

The maximum current for a power supply. This is the current which will flow when the two terminals of the power supply are connected by a short thick wire (low resistance of the wire).

Question 8

Equation for lost volts

Answer 8

Ir = E-V
E = V + Ir