Chapter 5 - Direct current circuits

Question 0

In series what is true about the current?

Answer 0

The current is the same everywhere

Question 1

At a junction in a circuit what is true?

Answer 1

The current leaving = the current entering

Question 2

In a series circuit what is true about voltage?

Answer 2

The sum of the potential differences going through the components = the potential difference of the cell

Question 3

In series what is true about resistance?

Answer 3

The sum of resistance = total resistance

Question 4

In parallel what is true about current?

Answer 4

The total current through the branches = the current through the cell

Question 5

In parallel what is true about voltage?

Answer 5

It is the same everywhere

Question 6

In parallel what is true about resistance?

Answer 6

1/The sum of the reciprocals of the branches = resistance through the cell

Question 7

Define the term internal resistance

Answer 7

Resistance inside the source of electrical energy when the current passes through it (loss of p.d. per unit current)

Question 8

What is the formula relating current, power and resistance/voltage?

Answer 8

P=IIR=IV

Question 9

What is the formula relating electromotive force, energy and charge?

Answer 9

Emf = E/Q

Question 10

What is the formula relating power, energy and time?

Answer 10

P=E/t

Question 11

What is the formula relating emf, current, resistor resistance (R), and internal resistance?

Answer 11

emf = I(R+r)

Question 12

What is the formula relating emf, voltage, internal resistance and current?

Answer 12

emf=V+Ir

Question 13

When is the maximum power delivered to the load?

Answer 13

When the loads resistance = internal resistance

Question 14

How can you plot v=emf-Ir on a graph?

Answer 14

y=mx+c

V=-Ir+emf

Question 15

On a graph how do you work out internal resistance?

Answer 15

Work out the gradient: change in voltage/ change in current

Question 16

What are the 4 top tips to circuit questions?

Answer 16

Draw digram with ruler, calculate cell current, work out current and resistance for each resistor, work out p.d. in parallel resistors - cell current*combined resistance, then *by a ratio or resistor in that branch

Question 17

If 2 cells are connected oppositely in series what should you do?

Answer 17

Subtract and resolve

Question 18

When n identical cells are in parallel what is the current through each cell?

Answer 18

I(r)/n

Question 19

How do you work out terminal potential difference for cells in parallel?

Answer 19

emf - Ir/n

Question 20

How much voltage do diodes have in the forward direction?

Answer 20

0.6V and infinite <0.6V

Question 21

Define the term potential divider

Answer 21

When 2 or more resistors in series are connected to a source of p.d.

Question 22

In a potential divider what formula links 2 different resistances and 2 different voltages?

Answer 22

V1/V2=R1/R2

Question 23

What can variable resistors be used for?

Answer 23

Controlling volume of a speaker or brightness of a bulb

Question 24

Define the term sensor circuit

Answer 24

Where the output p.d. changes a result of a physical variable (light/temperature)