Problem Statement:
A 120V battery supplies RL load through chopper. A freewheeling diode is connected across RL load having R=5Ω and L = 60mH. Load current varies between 7A and 9A. Calculate Ton/Toff for this chopper. Correct answer is '0.5'. Can you explain this answer? Explain in details.

Solution:
Understanding the problem:
We are given the following information:
- Supply voltage (Vs) = 120V
- Load resistance (R) = 5Ω
- Load inductance (L) = 60mH
- Range of load current (IL) = 7A to 9A
- We need to calculate Ton/Toff for this chopper.

Chopper Circuit:
The chopper circuit consists of a switch (S), a freewheeling diode (D), a load resistance (RL), and a DC voltage source (Vs). The circuit diagram is shown below.



When the switch (S) is closed, the current flows through the load (RL) and the switch (S) from the DC voltage source (Vs). When the switch (S) is opened, the current continues to flow through the load (RL) and the freewheeling diode (D) due to the inductance (L) of the load.

Determination of Ton/Toff:
The Ton/Toff ratio is defined as the ratio of the ON time of the switch (S) to the OFF time of the switch (S). It is given by the following formula:

Ton/Toff = IL/(Vs - VL)

Where,
- IL is the load current
- Vs is the supply voltage
- VL is the voltage across the load

The voltage across the load can be calculated using the following formula:

VL = IL * R + L * dIL/dt

Where,
- R is the load resistance
- L is the load inductance
- dIL/dt is the rate of change of load current

From the given information, we can calculate the voltage across the load (VL) for the minimum and maximum load currents.

For IL = 7A:
VL = 7 * 5 + 0.06 * (9 - 7)/0.01 = 35.12V

For IL = 9A:
VL = 9 * 5 + 0.06 * (9 - 7)/0.01 = 43.12V

Now, we can calculate Ton/Toff using the above formulas:

Ton/Toff = 7/(120 - 35.12) = 0.064
Ton/Toff = 9/(120 - 43.12) = 0.139

The average value of Ton/Toff is given by the following formula:

Ton/Toff (avg) = (Ton/Toff (min) + Ton/Toff (max))/2

Ton/Toff (avg) = (0.064 + 0.139)/2 = 0.102

Therefore, the calculated value of Ton/Toff is 0.102, which is not equal to the