Electromagnetism Check

Two small identical metal spheres, A and B, on insulated stands, are each given a charge of +2.0 x 10^-5 coulomb. The distance between the spheres is 2.0 x 10^-1 meter.  Calculate the magnitude of the electrostatic force that the charge on sphere A exerts on the charge on sphere B. 

• 90 N
• 18 N
• 66 N
• 130 N

Two small identical metal spheres, A and B, on insulated stands, sphere A has a charge of -3.9 x 10^-9 coulomb. The distance between the spheres is 5.4 meter with an electrostatic force of -5.2 N.  Calculate the charge on sphere B. 

• 4.3 cou
• 17 cou
• 150 cou
• 3.9 x 10⁹ cou

In which direction is the electrostatic force exerted on the electrons by the electric field in the diagram below?

• into the screen
• out of the screen
• towards the bottom
• towards the top

The magnitude of the electrostatic force between two point charges is F. If the distance between the charges is doubled, what is the electrostatic force between the charges?

• 2 times the force
• 1/2 the force
• 4 times the force 
• 1/4 the force

A wire in the plane of the page carries a current I directed toward the top of the page. If the wire is located in a uniform magnetic field B directed out of the page, what is the direction of the force on the wire resulting from the magnetic field?

• up
• down
• right 
• left

A balloon is rubbed back and forth across a person’ hair.  Afterward, she notices that when she holds the balloon close to her head, her hair stands up and is attracted toward the balloon. The balloon and hair were neutral before coming in contact with one another. Describe what is occurring with the electrical charges.

• balloon is negative, hair is positive
• balloon is positive, hair is negative
• balloon and hair are positive
• balloon and hair are negative

Two oppositely charged particles are held in place near each other. When the particles are released, what will most likely happen?

• the will move towards each other
• they will move away from each other
• they will not move
• they will start to sing show tunes

A student combs his hair with a plastic comb, and the hair becomes positively charged. What is the direction of the charge transfer?

• hair to comb
• comb to hair
• there is no transfer
• hair and comb to air

According to Einstein’s equation, what mass is equivalent to an energy of 2.8x10^-14 J?

• 2.5x10³ kg
• 3.2x10²⁸ kg
• 9,0x10¹⁶ kg
• 3.1x10^-31 kg

At a particular instant, an electron moves eastward at a speed V in a uniform magnetic field that is directed into a desk.  The magnetic force that acts on it is ___.

• north
• south 
• east
• west