Answer:
A solenoid is a device comprised of a coil of wire, the housing and a moveable plunger (armature). When an electrical current is introduced, a magnetic field forms around the coil which draws the plunger in. More simply, a solenoid converts electrical energy into mechanical work.
Explanation:
The coil is made of many turns of tightly wound copper wire. When an electrical current flows through this wire, a strong magnetic field/flux is created.
The housing, usually made of iron or steel, surrounds the coil concentrating the magnetic field generated by the coil.
The plunger is attracted to the stop through the concentration of the magnetic field providing the mechanical force to do work.
Explanation:
Work Done = Force * Displacement
= (4N)(10m) = 40J.
Power = Work Done / Time
= (40J)/(20s) = 2J/s = 2 Nm/sec.
Answer:
The one which falls on feet.
Explanation:
Because it exerts higher pressure as
P= F/ A
Larger the area less will be the pressure and less is the area larger will be the pressure.
Answer:
20.60 kV
Explanation:
Capacitance of parallel plates without dielectric between them is:
with d the distance between the plates, A the area of the plates and ε₀ the constant 
, so :
But the dielectric constant is defined as:
With C the effective capacitance (with the dielectric) and Co the original capacitance (without the dielectric). So, the new capacitance is:
But capacitance is related with voltage by:
with Q the charge and V the voltage, using the new capacitance and solving for V:
Answer:
energy is stored is 2.2 × 10⁻¹³ J
Explanation:
The capacitance of the cell is given with the expression
C = (KE₀A) / d
k is the dielectric constant, A is the area of the cell, d is the thickness of the cell.
Now given that; the diameter is 50,
Area A = 4πR²
A = 4π × ( 25 × 10⁻⁶ m)²
A = 7850×10⁻¹² m²
our capacitance C = (KE₀A) / d
C = [9 ( 8.85 × 10⁻¹² C²/N.m² × 7850×10⁻¹² m² )] / 7×10⁻⁹ m
C = 8.93 × 10⁻¹¹ F
Now Energy stored
E = 1/2 × CV²
E = 1/2 × (8.93 × 10⁻¹¹ F) × ( 70 × 10⁻³ V)²
E = 2.2 × 10⁻¹³ J
Therefore energy is stored is 2.2 × 10⁻¹³ J
