1) A Q1 = + 4.0 nC point charge and a Q1 = - 3.0 nC point charge are 6 cm apart on the x-axis. Find the point on the x -axis where the electric field...

1)   A Q1 = + 4.0 nC point charge and a Q1 = - 3.0 nC point charge are 6 cm apart on the x-axis.

Find the point on the x -axis where the electric field is zero.

Hint: Draw Electric vectors for both charges at a point between the two charge, and also at a point outside of the two charges on the right side of Q2 and on the left side of Q1

           Q1                                                                                                                                          Q2

2)   What is the net force on q 1 . The three charges are at the three vertices of an equilateral triangle ?( all angles are 60degrees)

q 1 =  - 1.0 nC

q 2 = - 2.0 nC

q 3 = + 3.0 nC

Equilateral side of the triangle = 4 cm.

Hint: Calculate forces acting on q1

You must show all the forces acting on q1. on the figure. Resolve each force in X and Y direction.

The find the F net in X and F net in Y. Use Pythagorean theorem the find the Net force.

                                                                                                           q 3                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              q 1                                                                                                                                                                          q 2          

3)

a)What is the current in a 150 W the filament of a light bulb when you turn the light on? Electric sockets supply electricity at about 120 V. 

b) What is the resistance of the filament?

c) What is your monthly payment if you keep the light bulb on 4 hours every day?

The cost of each kW (kilo watt) is 45 cents. (Give your answer is dollars.)

4)

a) Find the equivalent resistance(Req  ) in the circuit. Show formula, substitution and units.

R1 = 13Ω,  R2 = 5Ω,  R3 = 11Ω and voltage across the curcuit  V= 24 volts.

b) find electric current i1 , i2 ,i3 in each circuit.

Show formulas and all the steps.

5)

a)Define time constant of an R-C circuit ?

b) What is the time constant of a R_C circuit if Resistance is 10Ω and capacitance is 3.3 µF?

a)    What is the current of a 10Ω resistor if you connect it to 20 Volts battery?

b)    Define ohm's Law.