The de Broglie wavelength is λ=mvh. For an ideal gas, vrms=m3kT
Therefore: λ=3mkTh
Substituting values: λ=3×5.31×10−26×1.38×10−23×3006.63×10−34
λ=6.62×10−466.63×10−34=2.57×10−236.63×10−34
λ=2.58×10−11 m =25.8×10−12 m, so x≈26
JEE Main 2026 — Physics Modern Physics
The de Broglie wavelength of an oxygen molecule at 27∘C is x×10−12 m. The value of x is (take Planck's constant =6.63×10−34 J.s, Boltzmann constant =1.38×10−23 J/K, mass of oxygen molecule =5.31×10−26 kg)
Held on 23 Jan 2026 · Verified 6 Jul 2026.
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Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The electromagnetic wave exerts pressure on the surface on which they are allowed to fall. Reason (R): There is no mass associated with the electromagnetic waves. In the light of the above statements, choose the correct answer from the options given below :
The following diagram shows a Zener diode as a voltage regulator. The Zener diode is rated at $V_{z}=5 \mathrm{~V}$ and the desired current in load is 5 mA. The unregulated voltage source can supply upto 25 V. Considering the Zener diode can withstand four times of the load current, the value of resistor $R_{S}$ (shown in circuit) should be $\_\_\_\_$ $\Omega$. 
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The work function of a metal is 4.2 eV. The threshold wavelength for photoelectric emission is approximately:
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