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Physics Question 46 – JEE-MAIN 2026

Refer to the circuit diagram given below. The heat generated across the 6Ω resistance in 100 second is α100 J. The value of α is _______ . (Nearest integer)

To find the heat generated in a resistor, you first need to determine the current flowing through it.

Step 1: Apply Nodal Analysis to find the potential at the common node.✦ Active

Let the potential of the bottom wire be 0V. The potential at the node connected to the positive terminal of the 2V battery (left of 3Ω) is 2V. The potential at the node connected to the positive terminal of the 3V battery (right of 6Ω) is 3V. Let the potential of the central node (where 3Ω, 6Ω, and 4Ω meet) be VA. Applying Kirchhoff's Current Law (KCL) at node VA:

VA23+VA36+VA04=0

Multiplying by 12 (LCM of 3, 6, 4):

4(VA2)+2(VA3)+3VA=0

Simplifying the equation:

4VA8+2VA6+3VA=0 9VA14=0 VA=149V
Step 2: Calculate the current through the 6Ω resistor.○ Expand

The current I6Ω flowing from node VA towards the 3V battery is:

I6Ω=VA36=14936=142796=13/96=1354A

The magnitude of the current through the 6Ω resistor is |I6Ω|=1354A.

💡 Teacher's Secret Hint

Remember that the direction of current does not affect the heat generated, only its magnitude squared.

Step 3: Calculate the heat generated and the value of α.○ Expand

The heat generated H in the 6Ω resistor over time t=100 seconds is given by Joule's Law: H=I2Rt.

H=(1354)2×6×100=1692916×600=1014002916=8450243J

The problem states that the heat generated is α100 J. Therefore:

α100=8450243 α=8450×100243=8450002433477.366

Rounding to the nearest integer, the value of α is 3477.

💡 Teacher's Secret Hint

Pay close attention to the units and the form in which α is requested.

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