Resistance

Question 1

What is potential difference equivalent to? (also what’s its units?)

Answer 1

Voltage (JC^-1)

Question 2

Define electro motive force

Answer 2

The energy converted to electrical energy per unit of charge

Question 3

Define potential difference

Answer 3

A measure of energy, per unit of charge, transferred between two points in a circuit

[Energy converted from electrical potential energy to some other form per coulomb of change flowing from 1 point to the other]

(this is a retarded ass answer)

Question 4

What the equation that relates voltage to energy changes in a circuit per unit charge? (retarded ass question)

Answer 4

J = V x c

Work done = voltage x charge

Question 5

Look at the beginning of the first pages of the booklet

(because i cba to like explain this visual tasking type shit)

Answer 5

Well, u better get a good mark for this one, although this isn’t ideal or efficient (possibly?), it is what it is, Have Fun!

Question 6

What is Ohms law?

Answer 6

The current in a metal wire at a constant temp. is proportional to the p.d. across it

Question 7

What is the equation for voltage?

Answer 7

V = IR

Voltage = Current x Resistance

Question 8

Define resistance

Answer 8

Anything that opposes the flow of charge (aka current)

Question 9

What’s resistance measured in?

[but there’s also a chance that there may be more for this…?]

Answer 9

Ohms (that symbol that looks like a pimple)

[we shall see]

Question 10

Number 1 way of finding P?

Answer 10

Current x Voltage

Question 11

Number 2 way of finding P?

Answer 11

Current^2 x Resistance

I^2 x R

Question 12

Number 3 way of finding P?

Answer 12

Voltage^2 divided by Resistance

V^2 / R

Question 13

How does resistance work specifically in 3 steps?

Answer 13

1. As free electrons move thru wire, they collide with atoms + with one another, which slows them down
2. Some of the energy is transferred to the atoms, makes them vibrate = increases temp
3. Ye that’s resistance?

Question 14

What is the equation for resistivity?

Answer 14

Resistivity = (Resistance x Cross sectional area) divided by length

p = (RA)/L

Question 15

State what each of these symbols are:

p = ?
R = ?
A = ?
L = ?

Answer 15

p = resistivity
R = resistance
A = cross sectional area
L = length

Question 16

If temp. is low in a metal wire, what dat mean for the resistance?

(3 steps)

Answer 16

At low temperatures:

1. Electrons can drift past positive metal ions with ease
2. Cuz few collisions to slow em down
3. Resistance is low

Question 17

If temp. is high in a metal wire, what da mean for the resistance?

Answer 17

At high temperatures:

1. Positive ions vibrate with greater amplitude
2. Electron-in collisions more frequent
3. Flow of electrons slowed down
   [current reduced]
   RESISTANCE IS HIGH

Question 18

What’s the jig with resistance and resistivity

Answer 18

They directly proportional

You know what that means?

If resistance increases, resistivity increases

Question 19

Define semi conductor?

Answer 19

Component that can partially conduct electricity ig

Question 20

Why resistivity decrease with increasing temp. in semi conductors?

(3 steps)

Answer 20

1. More electrons break free of their atoms
2. Increase in number of electrons available for conduction
3. Resistivity decreases

Question 21

Define super conductor?

Answer 21

A material that has 0 electrical resistance at absolute zero temperature

Question 22

What name given to a temp, for a conductor that its resistance drops rapidly due to temp. change?

Answer 22

The Critical/transition

Question 23

What’s superconductivity?

(gl man)

Answer 23

When it has 0 electrical resistance when temp. is either at absolute zero (0 degrees kelvin or -273 degrees Celsius) to liquid nitro temps. (77k, -196 degrees Celsius)

Question 24

gagagaga

Answer 24

googoogoogo

Question 25

3 examples of use of superconductors?

Answer 25

1. Maglev train
2. MRI scanner
3. Particle accelerators

Question 26

Explain maglev train

(superconductor) 2 things

Answer 26

Makes train levitate off track

1. To produce strong magnetic field
2. no resistance = higher speeds

Question 27

Explain MRI scanner

(superconductor) 4 things

Answer 27

1. good for non-invasive medical diagnosis
2. Strong magnetic field aligns hydrogen atoms in body
3. Radio waves absorbed = emitted by hydrogen atoms
4. Image of body produced

Question 28

Explain particle accelerators

(superconductor) 2 things {that was separated} <– fuck is the use of that symbol

Answer 28

1. Magnetic field keeps the particles in a beam
2. And steers them around the circular detector