Chapter 10. D.C Circuits

Question 1

Note

Answer 1

For resistors in series, current is constant and voltage is the sum of all the p.d.s across the resistors and the total resistance is equal to the sum of the resistances of all the resistors.

Question 2

Note

Answer 2

For resistors in parallel, total current is split at junctions meaning total current is equal to the sum of all the currents going through each resistor and voltage across each resistor is the same and the total resistance is the reciprocal of the sum of the reciprocals of each resistor’s resistance(1/Rt = 1/R1 + 1/R2 + 1/R3 + …

Question 3

State Kirchoff’s first law

Answer 3

The total current flowing into a junction(point) is equal to the total current flowing out of the same junction.
-This is because charge is conserved, neither created nor destroyed

Question 4

Note

Answer 4

In a potential divider the more the resistance across the output voltage increases the more voltage comes out. As the temperature for a thermistor decreases its resistance increases. In a light dependent resistor, resistance decreases as light intensity increases.

Question 5

Note

Answer 5

A potentiometer is a potential divider. A rheostat is a variable resistor. Mak eusre you know how to use V_out = V_in x (R1 / (R1 + R2)) for a potentiometer

Question 6

Note

Answer 6

A battery is a combination of cells

Question 7

What is electmotive force?

Answer 7

The electrical potential energy transfered from other forms, per coulomb of charge that passes through a source, Volts

Question 8

State Kirchoff’s second law

Answer 8

Around any closed loop in a circuit, the sum of the e.m.fs is equal to the sum of all the p.d.s. Take note of the direction of conventional current

Question 9

Note

Answer 9

e.m.f = terminal p.d + lost volts for internal resistance