Charge and Current

Question 1

What is the definition of electric current?

Answer 1

Electric current is the rate of flow of charge- I=Q/t

Question 2

What is the charge of an electron?

Answer 2

1.6 x10^-19 coloumbs

Question 3

What is Kirchoff’s first law?

Answer 3

Kirchoff’s first law states that, for any point in an electrical circuit, the input of current to that point is equal to the output.

Question 4

What is the definition of mean drift velocity? [2]

Answer 4

The mean drift velocity is defined as the average velocity of electrons moving through a wire. (The average distance travelled per unit time for each electron)

Question 5

What is the definition of mean drift velocity?

Answer 5

Mean drift velocity is the average distance travelled by each electron per unit time.

Question 6

What is the formula for current using mean drift velocity.

Answer 6

I =Anev (current = cross-sectional area x number of free electrons x the charge of an electron x mean drift velocity

Question 7

What is the difference between of and emf?

Answer 7

Pd is the difference between voltage at two points on the circuit and EMf is the voltage supplied to the circuit from a source (power supply, solar panel etc…)

Question 8

What is the formula for the kinetic energy of an electron?

Answer 8

Voltage x e = 1/2mv^2

Question 9

What does the I-V graph of a resistor look like?

Answer 9

Resistors are ohmic, so I is directly proportional to V - a straight line going through the origin.

Question 10

What is an NTC resistor?

Answer 10

An NTC resistor is a Negative Temperature Coefficient resistor- resistance decreases as temperature increases as there is more free electrons.