MYIB / Honors Physics

Review Sheet: Electricity and Magnetism

A.  Conceptual Knowledge

1.  What is the charge of an atom?

2.  List three ways to charge an object.

3.  What is the charge on an object that has gained or lost electrons?

4.  What is the fundamental charge?

5.  How can a substance become polarized?

6.  What type of charges attract/repel?

7.  Draw the electric field lines around a point charge.

8.  Draw the electric field lines between a pair of like and unlike point charges.

9.  Draw the electric field lines between two oppositely-charged parallel plates.

10.  How does force change when charge or distance changes?

11.  What do these measure/detect? Electroscope, Voltmeter, Ammeter

12.  What causes certain elements to be ferromagnetic (natural magnets)?

13.  What would cause a natural magnet to lose magnetic properties?

14.  What would happen if a bar magnet is broken into pieces?

15.  Draw the magnetic field lines around a bar magnet.

16.  Draw the magnetic field pattern between the poles of two adjacent bar magnets.

17.  Describe where magnetic forces are strongest around a bar magnet.

18.  Describe how a magnet can be used to pick up some objects.

19.  Use right hand rule to determine the direction of magnetic force acting on a charged particle or a current carrying wire.

20.  Use right hand rule to determine the direction of a magnetic field around a current carrying wire.

21.  What is a compass? How does it work?

22.  What are some benefits of the Earth’s magnetic field?

23.  Describe the following

  1. Meter
  2. Motors
  3. Generators.
  4. How can the voltage be changed in a generator?

24.  How can current be induced?

25.  What is a transformer?

  1. Know the difference between a step up transformer and a step down transformer
  2. relate the number of coils to the voltage

26.  What is the difference between electric potential and electric potential energy?

B.  Problem Solving

1.  A sphere has a charge of −100 µC.

  1. Did the sphere gain or lose electrons?
  2. How many electrons did the sphere gain or lose?

2.  A metal sphere with a charge of −3 µC is brought in contact with a second metal sphere with a charge of +15 µC. After the spheres are separated, what is the charge on each sphere?

3.  A −5 µC charge is located 4.5 cm from a +2 µC charge. What electrostatic force exists between the charges? Is the force attractive or repulsive?

4.  Find the magnitude of the net electrostatic force on q1 shown in the diagram below.

5.  Determine the magnitude and direction of the force acting on a proton traveling 3.58 × 106 m/s horizontally north in a vertically upward magnetic field of strength 1.30 T.

6.  A proton with a speed of 1.80 × 106 m/s enters a 0.250 T magnetic field at an angle of 90o.

a.  What is the magnitude of the force?

b.  If the proton is moving down the page in a horizontal plane and the magnetic field is directed left in the plane of the page, what direction will the proton be deflected?

7.  The force on a wire carrying 25.0 A is a maximum of 5.25 N when placed between the poles of a magnet. If 32 cm of the wire is in the magnetic field, what is the approximate strength of the magnetic field?

8.  The rectangular loop of wire shown in the diagram is pushed into the magnetic field which points out of the page as shown. In what direction is current induced?

9.  A test charge experiences a field intensity of 3.0 x 105 N/C when located near a −3.0 μC point charge. How far away is the point charge from the test charge?

10.  An electric field does 12 J of work on a 0.0003 C charge. What is the magnitude of the voltage change?

11.  A voltmeter indicates that the difference in potential between two plates is 43 V. The plates are 0.38 m apart. What electric field intensity exists between them ?

Answers to Problems

1.  a) gain
b) 6.25 x 1014 / 2.  +6μC / 3.  −44.4 N attractive / 4.  196.2 N, right
5.  7.45 x 10−13 N; east / 6.  a) 7.2 x 10−14 N
b) in the page / 7.  .6563 T / 8.  clockwise
9.  0.3 m / 10.  40,000 V / 11.  113.2 N/C