🍇Grade 11 Physics T3 #2 (only study the starred cards)

Question 1

State Coulomb’s Law

Answer 1

The magnitude of the electrostatic force exerted by one point charge on another point charge is directly proportional to the product of the magnitudes of their charges and inversely proportional to the square of the distance between them.

Question 2

What are the units for the variables in the formula:

    k. Q1. Q2 F  = ----------  E              2
           r

Answer 2

F   : N
  E
                 9
k: 9 x 10
Q: C
r: m

NB! Q must not be written as negative! The magnitude of the force is calculated.

Question 3

What are the units for the variables in the formula:

    kQ E = -----
        2
       r

Answer 3

-1
E: N.C
               9
k: 9 x 10  (Coulomb's constant)
Q: C
r: m

Question 4

“Describe” an electric field

Answer 4

A region of space where an electric charge experiences a force. The direction of the electric field at a point is the direction that a positive test charge would move if placed at that point.

Question 5

What is electric field at a point?

Answer 5

The electrostatic force experienced per unit positive charge placed at that point

Question 6

What are the units for the variables in the formula:

    KQ E = -----
        2
       r

Answer 6

-1
E: N.C
               9
K: 9 x 10  (Coulomb's constant)
Q: C
r: m

Question 7

What are the units for the variables in the formula:

    F E = ---
    q

Answer 7

-1
E: N.C

F: N
q: Test charge

Question 8

What is a magnetic field or electric current represented by when it ‘goes into’ or ‘comes out of’ the page in a diagram?

Answer 8

Into page: a cross in a circle

Out of page: a dot in a circle

Question 9

What is a solenoid?

Answer 9

Many loops of wire forming a coil.

Question 10

What does it mean if field lines are parallel?

Answer 10

The field is uniform.

Question 11

What do you call many loops of wire forming a coil?

Answer 11

Solenoid

Question 12

What does an electromagnet consist of?

Answer 12

A piece of iron placed inside a solenoid.

Question 13

If there is a current through an electromagnet, what acts like a magnet?

Answer 13

The iron

Question 14

Name a use of electromagnets

Answer 14

Lifting metal (steel) objects
Electric bells
Magnetic strip to lock/unlock a door

Question 15

What can make an electromagnet stronger? (3)

Answer 15

Bigger current in conductor
More turns on coil
Type of material inside coil

Question 16

What are the environmental impacts of transmission lines? (4)

Answer 16

Land cleared
Trees kept away
Natural habitats destroyed
Possible health hazards from magnetic and electrical fields

Question 17

What can cause an induced EMF?

Answer 17

Relative motion between a magnetic field and a conductor

Question 18

What can increase an induced EMF? (3)

Answer 18

Magnet moves faster
More turns on coil
Stronger magnet

Question 19

What can change the direction of an induced current?

Answer 19

North vs South

Magnet pulled out vs pushed in

Question 20

Define magnetic flux

Answer 20

How the magnetic field changes

Change in magnetic field induces an EMF

Question 21

What are the units for the variables in the formula:

🚫=BAcos0

(🚫 being magnetic flux, 0 being theta)

Answer 21

🚫: Wb
B: T (magnetic field)

   2 A: m

Question 22

State Faraday’s Law

Answer 22

The induced EMF in a circuit is equal to the rate of change of magnetic flux through the circuit.

Question 23

What are the units for the variables in the formula:

   -N. 🔺🚫 E = ---------
        🔺t

Answer 23

E: V
N: (no. of turns on coil)
🔺🚫: Wb (change in flux)
🔺t: s (time interval)

Question 24

What are the environmental impacts of transmission lines? (4)

Answer 24

Land cleared
Trees kept away
Natural habitats destroyed
Possible health hazards from magnetic and electrical fields

Question 25

What can cause an induced EMF?

Answer 25

Relative motion between a magnetic field and a conductor

Question 26

What can increase an induced EMF? (3)

Answer 26

Magnet moves faster
More turns on coil
Stronger magnet

Question 27

What can change the direction of an induced current?

Answer 27

North vs South

Magnet pulled out vs pushed in

Question 28

Define magnetic flux

Answer 28

How the magnetic field changes

Change in magnetic field induces an EMF

Question 29

Name four measurements of charge and say how many of those units would be needed to make up one Coulomb.

Answer 29

3
10 mC = 1 C

6 10   uC = 1C

9 10   nC = 1C

12 10    pC = 1C

Question 30

A coil is not moving in a magnetic field. Which of the following will there be in the system?

Magnetic field (B)
Magnetic flux
Induced EMF

Answer 30

Magnetic field: yes
Magnetic flux: yes
Induced EMF: no (there is no change in magnetic flux)

Question 31

Transformers consist of 3 main components. What are they?

Answer 31

Iron core
Primary coil
Secondary coil

Question 32

What causes electromagnetic induction?

Answer 32

Relative motion between a conductor and a magnetic field. (Causes a change in magnetic flux, which creates an induced EMF)