Explanation:
Power of electric kettle, P = 1 kW
Voltage, V = 220 V
(a) Electric power is given by the formula as follows :
R is resistance
(b) When connected to a 220 V supply, it takes 3 minutes for the water in the kettle to reach boiling point.
Energy supplied is given by :
P is power,
To solve this problem we will apply the concepts related to the Magnetic Force, this is given by the product between the current, the body length, the magnetic field and the angle between the force and the magnetic field, mathematically that is,
Here,
I = Current
L = Length
B = Magnetic Field
= Angle between Force and Magnetic Field
But
Rearranging to find the Magnetic Field,
Here the force per unit length,
Replacing with our values,
Therefore the magnitude of the magnetic field in the region through which the current passes is 0.0078T
Answer:
The efficiency of the system is 63.7 %
Explanation:
Given;
input power of the motor, = 1.5 kW = 1,500 W
mass of the car lifted, m = 1300 kg
height through which the car was lifted, h = 1.8 m
time, t = 24 s
The output power of the motor is calculated as;
Output Power = F x v
= (mg) x (d/t)
= (1300 x 9.8) x (1.8 / 24)
= 12,740 x 0.075
= 955.5 W
The efficiency of the system is calculated as;
The correct answer is 63.7%