4. Which one of the following equations for power is incorrect?
a. P=IR
b. P=W/t
c. P=IV
d. P=V^2 /R
a. P = I^2 R
To determine which equation for power is incorrect, we need to look at the definitions and formulas of power in physics.
In physics, power is defined as the rate at which work is done or the rate at which energy is transferred or converted. It is usually measured in watts (W).
Let's analyze each equation for power:
a. P = IR
This equation represents the relationship between power (P), current (I), and resistance (R) in an electrical circuit. According to Ohm's Law, the current passing through a conductor is directly proportional to the voltage applied and inversely proportional to the resistance. Therefore, this equation is correct.
b. P = W/t
This equation represents the relationship between power (P), work (W), and time (t). Power is equal to the work done divided by the time taken to do the work. This equation is correct.
c. P = IV
This equation represents the relationship between power (P), current (I), and voltage (V). In an electrical circuit, power can be calculated by multiplying the current flowing through the circuit by the voltage across the circuit. This equation is also correct.
d. P = V^2/R
This equation represents the relationship between power (P), voltage (V), and resistance (R). According to Ohm's Law, the power dissipated in a circuit can be calculated by dividing the square of the voltage across the circuit by the resistance. Therefore, this equation is correct.
From the above analysis, we can conclude that all the given equations for power are correct. None of them are incorrect.