10 Electricla Circuits

Question 1

Kirchhoff’s second/ Voltage law

Answer 1

Σε = ΣV around a closed loop

Question 2

internal resistance equation

Answer 2

ε = V + lost volts
ε = V + Ir
ε = I(R+r)

Question 3

effect on voltage and current when connecting cells in parallel and series

Answer 3

in series:
voltage increases

in parallel:
current increases

Question 4

investigating internal resistance

Answer 4

measure terminal p.d. for different values of current. use variable resistor change

ε = V + Ir

V = -rI + ε

y = mx +c

m = -r, c = ε

Question 5

High or low internal resistance?

Answer 5

Like car batteries, many rechargeable batteries, including those in mobile phones and laptops as well as the more traditional tvpes, have a small internal resistance. This allows them to be recharged using higher currents without overheating or wasting a lot of energy, so that recharging is fast. Some batteries in mobile phones charge to 80% capacity from flat in under an hour.
In contrast, the high-voltage power supplies used in classrooms have a very high internal resistance (often millions of ohms). This acts as a safety feature, preventing the power supply from delivering a fatal electric current.

Question 6

potential divider equation

Answer 6

ratio of resistance
V1/V2 = R1/R2

divider equation
Vout = (R2/(R1+R2)) * Vin