# Physics

posted by
**Jonathan**
.

PLEASE HELP WITH AS MANY AS POSSIBLE... I AM TERRIBLY CONFUSED.

1. A charge moves a distance of 1.7 cm in the

direction of a uniform electric field having

a magnitude of 200 N/C. The electrical

potential energy of the charge decreases by

9.69095 × 10−19 J as it moves.

Find the magnitude of the charge on the

moving particle. (Hint: The electrical poten-

tial energy depends on the distance moved in

the direction of the field.)

Answer in units of C

2. Initially, both metal spheres are neutral.

In a charging process, 1 × 1013 electrons are

removed from one metal sphere and placed on

a second sphere. Then the electrical poten-

tial energy associated with the two spheres is

found to be −0.061 J .

The Coulomb constant is 8.98755 ×

109 N · m2/C2 and the charge on an electron

is 1.6 × 10−19 C.

What is the distance between the two

spheres?

Answer in units of m.

3. It takes 119 J of work to move 2.4 C of charge

from a positive plate to a negative plate.

What voltage difference exists between the

plates?

Answer in units of V

4The magnitude of a uniform electric field be-

tween the two plates is about 2 × 105 N/C.

If the distance between these plates is

0.1 cm, find the potential difference between

the plates.

Answer in units of V

5A force of 3.60 × 10−2 N is needed to move a

charge of 56.0 μC a distance of 25.0 cm in the

direction of a uniform electric field.

What is the potential difference that will

provide this force?

Answer in units of V.

6An electron moves from one plate of a capaci-

tor to another, through a potential difference

of 2495 V.

a) Find the speed with which the electron

strikes the positive plate.

Answer in units of m/s.

7b) If a proton moves from the positive plate to

the negative plate, find the speed with which

the proton strikes the negative plate.

Answer in units of m/s.

008

A proton is accelerated from rest through a

potential difference of 119 V.

Calculate the final speed of this proton.

Answer in units of m/s.

9. The three charges shown in the figure are

located at the vertices of an isosceles triangle.

The Coulomb constant is 8.98755 ×

109 N · m2/C2 and the acceleration of grav-

ity is 9.8 m/s2 .

4.1 cm

4.1 cm

1.4 cm

+

− − 3.3 × 10−9 C 3.3 × 10−9 C

5.1 × 10−9 C

Calculate the electric potential at the mid-

point of the base if the magnitude of the posi-

tive charge is 5.1×10−9 C and the magnitude

of the negative charges are 3.3 × 10−9 C.

Answer in units of V.

10. An electron that is initially 54 cm away from

a proton is displaced to another point.

The Coulomb constant is 8.98755 ×

109 Nm2/C2 and the acceleration of gravity

is 9.8 m/s2.

If the change in the electrical potential

energy as a result of this movement is

2.7 × 10−28 J, what is the final distance be-

tween the electron and the proton?

Answer in units of m.

11A potential difference of 117.0 V exists across

the plates of a capacitor when the charge on

each plate is 429.0 μC.

What is the capacitance?

Answer in units of F.

12A parallel-plate capacitor has a plate area of

188 cm2 and a plate separation of 0.0420 mm.

The permittivity of a vacuum is 8.85419 ×

10−12 C2/N · m2.

a) Determine the capacitance.

Answer in units of F.

13b) Determine the potential difference when

the charge on the capacitor is 530.0 pC.

Answer in units of V.

14A parallel-plate capacitor has a capacitance

of 0.28 μF and is to be operated at 6500 V.

a) Calculate the charge stored.

Answer in units of C

15b) What is the electrical potential energy

stored in the capacitor at the operating po-

tential difference?

Answer in units of J.