Answers:
a) 
We know the Earth's surface area in square miles is:

On the other hand, we know
.
Then:

b) 
In this part, we can work with the obtained value in part a:

And knowing 
Hence:

c) 
Knowing
:

Answer:
Explanation:
Electric force between two particles
= ( 9x10⁹x7.4 x 10⁻⁶ x 3.2 x 10⁻⁶ )/ (3.2 x 10⁻²)² ( Distance between particles is 1.6 +1.6 = 3.2 cm . )
= 20.81 x 10 = 208.1 N
1 ) Magnetic field due to movement of second charge
= 
= 10⁻⁷ x 3.2 x 10⁻⁶ x 4 / (3.2 x 10⁻²)²
B = 1.25 x 10⁻⁹ T.
Due to this magnetic field , there is a force called magnetic force on first particle which will be expressed as follows
Force = Bqv
= 1.25 x 10⁻⁹ x 7.4 x 10⁻⁶ x 4
37 x 10⁻¹⁵ N
2 ) For magnetic force to be equal to electric force let velocity o particles be V
Then magnetic field due to second charge
= 10⁻⁷ x 3.2 x 10⁻⁶ x v / (3.2 x 10⁻²)²
= .3125 v x 10⁻⁹
Magnetic force on first charge
Bqv
= .3125 v x 10⁻⁹ x 7.4 x 10⁻⁶ x v
2.3125 x 10⁻¹⁵ v²
magnetic force = electric force
2.3125 x 10⁻¹⁵ v² = 208.1
v² = 90 x 10¹⁵
v² = 900 x 10¹⁴
v = 30 x 10⁷ m /s
Answer:
1. 2.64 kJ 2. 50 W 3. 2.5 A
Explanation:
1. Energy transformed in the lamp, E = IVt where I = current = 0.22 A, V = voltage = 120 V and t = time = 100s
E = 0.22 A × 120 V × 100 s
= 2640 J
= 2.64 kJ
2. The rate at which energy is trans ferred to the resistor is the power.
Power, P = IV where I = current = 5.0 A and V = voltage = 10 V
P = 5.0 A × 10 V = 50 W
3. Since Power P = IV
Current through the heater I = P/V P = 30 W and V = 12 V
I = 30 W/12 V
= 2.5 A
And the answer is False.
It will help you.