🍇Grade 11 Physics T3 #2 (only study the starred cards) Flashcards
State Coulomb’s Law
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.
What are the units for the variables in the formula:
k. Q1. Q2 F = ---------- E 2
r
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.
What are the units for the variables in the formula:
kQ E = -----
2
r
-1
E: N.C
9
k: 9 x 10 (Coulomb's constant)
Q: C
r: m“Describe” an electric field
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.
What is electric field at a point?
The electrostatic force experienced per unit positive charge placed at that point
What are the units for the variables in the formula:
KQ E = -----
2
r
-1
E: N.C
9
K: 9 x 10 (Coulomb's constant)
Q: C
r: mWhat are the units for the variables in the formula:
F E = ---
q
-1
E: N.C
F: N
q: Test charge
What is a magnetic field or electric current represented by when it ‘goes into’ or ‘comes out of’ the page in a diagram?
Into page: a cross in a circle
Out of page: a dot in a circle
What is a solenoid?
Many loops of wire forming a coil.
What does it mean if field lines are parallel?
The field is uniform.
What do you call many loops of wire forming a coil?
Solenoid
What does an electromagnet consist of?
A piece of iron placed inside a solenoid.
If there is a current through an electromagnet, what acts like a magnet?
The iron
Name a use of electromagnets
Lifting metal (steel) objects Electric bells Magnetic strip to lock/unlock a door
What can make an electromagnet stronger? (3)
Bigger current in conductor
More turns on coil
Type of material inside coil
What are the environmental impacts of transmission lines? (4)
Land cleared
Trees kept away
Natural habitats destroyed
Possible health hazards from magnetic and electrical fields
What can cause an induced EMF?
Relative motion between a magnetic field and a conductor
What can increase an induced EMF? (3)
Magnet moves faster
More turns on coil
Stronger magnet
What can change the direction of an induced current?
North vs South
Magnet pulled out vs pushed in
Define magnetic flux
How the magnetic field changes
Change in magnetic field induces an EMF
What are the units for the variables in the formula:
🚫=BAcos0
(🚫 being magnetic flux, 0 being theta)
🚫: Wb
B: T (magnetic field)
2 A: m
State Faraday’s Law
The induced EMF in a circuit is equal to the rate of change of magnetic flux through the circuit.
What are the units for the variables in the formula:
-N. 🔺🚫 E = ---------
🔺t
E: V
N: (no. of turns on coil)
🔺🚫: Wb (change in flux)
🔺t: s (time interval)
What are the environmental impacts of transmission lines? (4)
Land cleared
Trees kept away
Natural habitats destroyed
Possible health hazards from magnetic and electrical fields
What can cause an induced EMF?
Relative motion between a magnetic field and a conductor
What can increase an induced EMF? (3)
Magnet moves faster
More turns on coil
Stronger magnet
What can change the direction of an induced current?
North vs South
Magnet pulled out vs pushed in
Define magnetic flux
How the magnetic field changes
Change in magnetic field induces an EMF
Name four measurements of charge and say how many of those units would be needed to make up one Coulomb.
3
10 mC = 1 C
6 10 uC = 1C 9 10 nC = 1C 12 10 pC = 1C
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
Magnetic field: yes
Magnetic flux: yes
Induced EMF: no (there is no change in magnetic flux)
Transformers consist of 3 main components. What are they?
Iron core
Primary coil
Secondary coil
What causes electromagnetic induction?
Relative motion between a conductor and a magnetic field. (Causes a change in magnetic flux, which creates an induced EMF)
