First electromagnet
Explanation:
The first electromagnet is the strongest and it is stronger than the given electromagnet above. 
An electromagnet is a temporary magnet made by passing current through a wire wounded round an iron core or metallic core. 
- When current is passed through, the metal becomes magnetic. 
- The strength of the electromagnet depends on the number of coil round the metal core and also the intensity of current passed through it. 
- The higher the number of coils wounded round the metal core, the stronger the electromagnet that will be produced. 
- Also, the higher the intensity of electricity passed through the wire, the stronger it is. 
learn more: 
Electromagnet brainly.com/question/2191993
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<em><u>One</u></em>
Givens
- delta B = 0.20 T/s
- A = 0.07 m^2
- R = 3.5 ohms
Formula
Φ = ΔB*A
e = Φ 
Solution (first part)
e = 0.2 * 0.07
e = 0.014 emf
Solution (second part)
i = e/R
i = 0.014 / 3.5
i = 4 * 10^-3
i = 4 ma
Answer 
A
<em><u>Two</u></em>
Givens
N = 200 turns
Φ = 30 degrees
Delta B = 0.45 T/s
phi = 30 degrees
r = 0.06 meters
Formula
e = -N * delta B * A * Cos(phi)
Solution
e = -200 * 0.45 (pi r^2) * Cos(30)
e = - 200 * 0.45 * (3.14 * 0.06^2) * cos(30)
e = 0.881 emf
Answer
A
 
        
             
        
        
        
The best technique to separate an insoluble solid from a liquid is filtration. Filtration is a process that separates solids from liquid by adding a medium, such as a filter paper, that only liquid can pass, and what is left behind the filter paper is the insoluble solid.
        
                    
             
        
        
        
Answer:
t = 4.28 s
Explanation:
The horizontal speed of a marble = 7 m/s
The horizontal displacement covered by the marble = 30 m
We need to find the time for which the marble is in air. Let the time is t. Using the formula for speed to find it as follows :

So, it will in the air for 4.28 s.