Answer:
In coin card experiment smooth card is used so that the card can slide easily from glass
Explanation:
It is given that,
Area of nickel wire, 
Resistance of the wire, R = 2.4 ohms
Initial value of magnetic field, 
Final magnetic field, 
Time, t = 1.12 s
Let I is the induced current in the loop of wire over this time. Te emf induced in the wire is given by Faraday's law as :






Induced current in the loop of wire is given by :



So, the induced current in the loop of wire over this time is
. Hence, this is the required solution.
Answer:
0.92 μC
Explanation:
In a parallel-plate capacitor, the electric field formed is equal to the charge density divited by the vacuum permisivity e0, as there are no dielectric between the plates. e0 is equal to 8.85*10^-12 C^2/Nm^2. The charge density is the total charge of each individual plate divided by its area. Then, the maximum charge allowed will be equal to:

or 0.92 μC
Answer:
The half-life is 
Explanation:
Using the decay equation we have:

Where:
- λ is the decay constant
- A(0) the initial activity
- A is the activity at time t
We know the activity decrease by a factor of two in a one hour period (t = 1 h), it means that


Taking the natural logarithm on each side we have:


Now, the relationship between the decay constant λ and the half-life t(1/2) is:




I hope it helps you!