JEE Main 2020 (Online) 9th January Evening Slot | Dual Nature of Radiation Question 76 | Physics

JEE Main 2020 (Online) 9th January Evening Slot

MCQ (Single Correct Answer)

-1

The energy required to ionise a hydrogen like ion in its ground state is 9 Rydbergs. What is the wavelength of the radiation emitted when the electron in this ion jumps from the second excited state to the ground state ?

35.8 nm

11.4 nm

8.6 nm

24.2 nm

JEE Main 2020 (Online) 9th January Evening Slot

MCQ (Single Correct Answer)

-1

An electron of mass m and magnitude of charge |e| initially at rest gets accelerated by a constant electric field E. The rate of change of de-Broglie wavelength of this electron at time t ignoring relativistic effects is :

$${{ - h} \over {\left| e \right|Et}}$$

$${{ - h} \over {\left| e \right|E\sqrt t }}$$

$${{ - h} \over {\left| e \right|E{t^2}}}$$

$${{\left| e \right|Et} \over h}$$

JEE Main 2020 (Online) 9th January Morning Slot

MCQ (Single Correct Answer)

-1

A particle moving with kinetic energy E has de Broglie wavelength $$\lambda $$. If energy $$\Delta $$E is added to its energy, the wavelength become $$\lambda $$/2. Value of $$\Delta $$E, is :

JEE Main 2020 (Online) 9th January Morning Slot

MCQ (Single Correct Answer)

-1

Radiation, with wavelength 6561 $$\mathop A\limits^o $$ falls on a metal surface to produce photoelectrons. The electrons are made to enter a uniform magnetic field of 3 × 10^–4 T. If the radius of the largest circular path followed by the electrons is 10 mm, the work function of the metal is close to :

1.8eV

0.8eV

1.1eV

1.6eV

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