Electric Circuits

Question 1

What is the electric current (I)

Answer 1

The rate of flow of charged particles

Question 2

What is the equation for the electric current?

Answer 2

I = ∆Q/ ∆t

Question 3

What is voltage?

Answer 3

1 volt -> potential difference between two points when 1 joule of work is done to move a charge of 1 coulomb.

Question 4

What’s the equation for voltage?

Answer 4

V = W/ Q

Question 5

what is the electric current’s SI unit

Answer 5

Ampere

Question 6

what is the solid definition of Ampere (A)?

Answer 6

The current flowing in two parallel wires 1m apart in a vacuum such that there is an attractive force of 2 * 10^7 N per meter length between them

Question 7

what is 1 Ampere equal to

Answer 7

1 ampere -> 1 Coulomb of charge passing a point in 1 second

Question 8

In what direction does the conventional charge flow?

Answer 8

From positive to negative

Question 9

In what direction do the electrons flow in a circuit?

Answer 9

From negative to positive

Question 10

What device do we use to measure the current?

Answer 10

The ammeter

Question 11

how do we use the ammeter

Answer 11

It goes in series with the other parts of the circuit

Question 12

what is the mass of an electron?

Answer 12

9.1 * 10^-31 kg

Question 13

what is elementary charge equal to?

Answer 13

1.6 * 10^ -19 Coulomb

Question 14

What is the definition of a coulomb

Answer 14

The charge that flows past a point in 1 second when there is a current of 1 amp

Question 15

What is the equation for the charge?

Answer 15

∆Q = I * ∆t

Question 16

What is Kirchhoff’s 1st Law?

Answer 16

at any point in an electrical circuit, the sum of currents into that point is equal to the sum of currents out, electrical charge is conserved.

Question 17

what is the cross-sectional area equal to?

Answer 17

A = π d^2 / 4

Question 18

what is the volume equal to

Answer 18

V = Length * Area

Question 19

what is the equation for the no. of free electrons

Answer 19

volume * charge density | nL A

Question 20

Total charge free to move =

Answer 20

= nLAe

Question 21

Time for charge to leave this bit of wire =

Answer 21

= length / drift velocity

Question 22

Another derivation of I = Q / T is

Answer 22

I = n A v e

Question 23

what is the velocity equal to

Answer 23

v = n A e / I

Question 24

what is the electro-motive force

Answer 24

EMF is the energy per unit charge transferred from chemical energy into electrical energy

Question 25

what tool do you use to calculate the potential difference in a circuit?

Answer 25

A Voltmeter

Question 26

what does the voltmeter need to have?

Answer 26

High resistance

Question 27

what is the difference between a voltmeter and an ammeter?

Answer 27

A voltmeter measures the electrical potential across that component, an ammeter measures goes in series and measures the current through a position

Question 28

What’s the difference between emf and potential difference?

Answer 28

both measures in volt, but EMF is the energy per unit charge transferred from chemical to electrical, potential difference is the energy per unit charge transferred from electrical into other forms

Question 29

what is the potential difference?

Answer 29

the energy per unit charge transferred from electrical into other forms

Question 30

what is the voltage equal to

Answer 30

v = IR

Question 31

The relation ship between voltage and current is

Answer 31

Directly proportional

Question 32

The relationship between current and resistance is

Answer 32

Inversely proportional

Question 33

Ohm’s Law states that

Answer 33

Ohm’s law states that electric current through a conductor between two points is directly proportional to the voltage across the two points.

Question 34

kirchhoff’s 2nd law states that

Answer 34

As you go around a voltage in. a loop the total voltage = 0