Answer:
(a) 
(b) neither increasing or decreasing
(c) opposite to the flow of charge carriers
Explanation:
The current through an inductor of inductance L is given by:
(1)
(a) The induced emf is given by the following formula
(2)
You derivative the expression (1) in the expression (2):

(b) At t=0 the current is zero
(c) At t = 0 the emf is:

w, L and Imax have positive values, then the emf is negative. Hence, the induced emf is opposite to the flow of the charge carriers.
(d) read the text carefully
Answer:
7.39 m/s
Explanation:
Applying
K.E = 1/2mv²..................... Equation 1
Where K.E = Kinetic Energy, m = mass of the ball, v = velocity of the ball.
Make v the subject of the equation
v = √(2K.E/m)................. Euqation 2
From the question,
Given: K.E = 30 J, m = 1.1kg
Substitute these values into equation 2
v = √(2×30/1.1)
v = √54.54
v = 7.39 m/s
Answer: 1 / 4.283 x 10¹¹
the earth model will be 64 cm away from the tennis ball
Explanation:
0.03 / 7 x 10⁸ = 1 / 4.283 x 10¹¹
(1.5 x 10¹⁰)( 1 / 4.283 x 10¹¹) = 0.64285
I like to just keep writing them over and over on a page also if you remember them just before the exam than as soon as you start write them on the front of your test so you don’t forget them.
Hope this helps.