Answer:
The mass of the cube is 420.8 kg.
Explanation:
Given that,
Length of edge = 38.9 cm
Density 
We need to calculate the volume of cube
Using formula of volume


We need to calculate the mass of the cube
Using formula of density




Hence, The mass of the cube is 420.8 kg.
Given that,
Current = 4 A
Sides of triangle = 50.0 cm, 120 cm and 130 cm
Magnetic field = 75.0 mT
Distance = 130 cm
We need to calculate the angle α
Using cosine law




We need to calculate the angle β
Using cosine law




We need to calculate the force on 130 cm side
Using formula of force



We need to calculate the force on 120 cm side
Using formula of force


The direction of force is out of page.
We need to calculate the force on 50 cm side
Using formula of force


The direction of force is into page.
Hence, The magnitude of the magnetic force on each of the three sides of the loop are 0 N, 0.1385 N and 0.1385 N.
1) Current in the wire: 0.0875 A
The current in the wire is given by:

where
Q is the charge passing a given point in the conductor
t is the time elapsed
In this problem, we have
Q = 420 C is the total charge passing through a given point in a time of
t = 80 min = 4800 s
So, the current is

2) Drift velocity of the electrons: 
The drift velocity of the electrons in the wire is given by:

where
I = 0.0875 A is the current
is the number of free electrons per cubic meter
A is the cross-sectional area
is the charge of one electron
The radius of the wire is

So the cross-sectional area is

So, the drift velocity is

Answer:
A). σ = 3.823 x
/N-
B).
C/
C).
J
Explanation:
A). We know magnitude of charge per unit area for a conducting plate is given by

where, E is resultant electric field = 1.2 x
V/m
is permittivity of free space = 8.85 x
/N-
k is dielectric constant = 3.6
∴
= 3.6 x 8.85 x
x 1.2 x 
= 3.823 x
/N-
B).Now we know that the magnitude of charge per unit area on the surface of the dielectric plate is given by


C/
C).
Area of the plate, A = 2.5 
= 2.5 x 

diameter of the plate, d = 1.8 mm
= 1800 m
∴ Total energy stored in the capacitor


J
Answer:
0.5 m
Explanation:
Givens:
ym1 = 2.5 mm
ym2 = 4.5 mm
Ф_1=π / 4
Ф_2=π / 2
We have 2 ways to solve this problem. The first one given that the 2 waves have the frequency then we know that the resultant wave amplitude is
Ym = (ym1 + ym2)cos(Ф_2/2)
By substitution we have
Ym= (0.025 + 0.045)cos(π/4) = 0.496 m
The second one is it treat them as Phasors where the phase between them is Ф_2=π / 2 Therefore
Ym^2=(ym1^2+ym2^2)
So we have Ym=√0.025^2+0.045^2
= 0.5 m