Shane's 100-watt radio draws 7 amps of current on a 120-volt circuit. What is the resistance in the radio?
1 answer:
Answer:
Resistance, R = 2.04 Ohms.
Explanation:
Given the following data;
Current = 7 amps
Circuit voltage = 120 Volts
Power = 100 Watts
To find the resistance;
First of all, we would calculate the potential difference (voltage level) used by the radio.
Power = current * voltage
100 = 7 * voltage
Voltage = 100/7
Voltage = 14.29 Volts
Next, we solve for the resistance of the radio;
Ohm's law states that at constant temperature, the current flowing in an electrical circuit is directly proportional to the voltage applied across the two points and inversely proportional to the resistance in the electrical circuit.
Mathematically, Ohm's law is given by the formula;
Where;
V represents voltage measured in voltage.
I represents current measured in amperes.
R represents resistance measured in ohms.
Substituting into the formula, we have;
Resistance, R = 2.04 Ohms.
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(a) the mass flow rate of air is 5.351 kg/s
(b) the input power required is 2090.786 kW
Explanation:
Given;
initial pressure, P₁ = 100 kPa
initial temperature, T₁ = 20 °C
Final pressure, P₂ = 1.8 MPa
Final temperature, T₂ = 400 °C
Inlet area of the compressor = 0.15 m²
outlet area of compressor = 0.078 m²
velocity of air = 30 m/s
Part (a) mass flow rate of air through the inlet
Mass flow rate = Area x velocity = density x volumetric rate
m = Av = ρV
from ideal gas law, PV = nRT and ρ = m/V
substitute these values in the above equations, we will have;
Part (b) the required power input
where;
W is the input power
m is the mass flow rate
h₁ is the initial enthalpy
h₂ is the final enthalpy
initial and final enthalpy are obtained from steam table using interpolation;
h₁ = 293.166 kJ
h₂ = 684.344 kJ