2026 · Paper 2 · Physics

Question 2

The printed question, the official key, and each model’s JSON answer plus the reasoning it wrote.

PhysicsPaper 2Single correct

Q02

Official A

JEE Advanced 2026 Paper 2 Physics question 2

Model answers

Claude Fable 5.1

Anthropic

Correct3 / 3

A

Claude Fable 5.1 reasoning

N(t) = (α/λ)(1 − e^{−λt}). Decay rate = λN = α(1 − e^{−λt}). Power = αE0(1 − e^{−λt}) = ms dT/dt, so dT/dt = αE0/(ms) (1 − e^{−λt}).

GPT 6 Astra

OpenAI

Correct3 / 3

A

GPT 6 Astra reasoning

**Simplifying calculations** I need to solve a straightforward equation, focusing on parameters like N, alpha, and lambda at initial values. I'm thinking of formats that could work to present my results clearly, maybe to deliver in just JSON format as the user requested. That might streamline things. So, I'll summarize the derivation and keep it as concise as possible, aiming to use JSON only for clarity and directness. Let's give that a try!

GPT 5.5

OpenAI

Correct3 / 3

A

GPT 5.5 reasoning

No written reasoning was returned for this item.

Claude Sonnet 5

Anthropic

Correct3 / 3

A

Claude Sonnet 5 reasoning

I'm setting up the decay equation for N(t) with production rate α and decay constant λ, then deriving the decay rate and power output as functions of time, leading to the temperature rate dT/dt scaling with (1-e^{-λt}). This points toward answer A.