CH 11 - Electrcity

Question 1

what is Kirchhoff’s second law?

Answer 1

• takes the law of conservation of energy and applies it to electrical circuits.
• the sum of the electromotive force is equal to the sum of all the p.d.s. around a closed loop.

Question 2

what is a series circuit?

Answer 2

a type of electrical circuit where the components are connected end-to-end.
there is only path for the current.

Question 3

what is a parallel cirucit?

Answer 3

a type of branching circuit in which there is more than one path for current- components in parralel have the same potential difference.

Question 4

rule for resistance in series circuits?

Answer 4

R = R₁ + R₂ +…

Question 5

rule for resistance in parallel circuits?

Answer 5

1/R = 1/R₁ + 1/R₂ +….

Question 6

What is internal resistance?

Answer 6

resistance of a source of emf due to its construction, which causes a loss of energy as charge passes through the source.

Question 7

What affect does increase in current have on the lost volts/

Answer 7

emf = terminal p.d. + lost volts

therefore increase in lost volts

Question 8

what is terminal p.d.?

Answer 8

• voltage measured across terminals
• equals emf when no current flows
• less than emf when current flows due to internal resistance.

Question 9

What are potential divider circuits?

Answer 9

these circuits can vary the p.d. across an output when connected to a fixed input.

Question 10

What is a potentiometer?

Answer 10

a potentiometer is a variable resistor with three terminals and a sliding contact. Adjusting this contact varies the p.d. between two of the terminals, giving a varibale V out.
-potentiometers can be made very compact,making them useful forportable electronic devices.