## Question

### Solution

Correct option is Energy emitted by the bulb = 25 watt = 25 J s–1  (âˆµ 1 watt = 1 Js–1

Energy of one photon (E) = hv Hence,    ∴ No. of photons emitted per sec #### SIMILAR QUESTIONS

Q1

Calculate the uncertainty in the velocity of a wagon of mass 3000 kg whose position is known to an accuracy of ±10 pm

(Planck’s constant = 6.63 × 10–34 Js)

Q2

Calculate the uncertainty in the position of an electron if the uncertainty in its velocity is 5.7 × 105 m/sec (h = 6.6 × 10–34 kg m2 s–1, mass of the electron = 9.1×10–31 kg).

Q3

A golf ball has a mass of 40 g and a speed of 45 m/s. If the speed can be measured within accuracy of 2%, calculate the uncertainty in position.

Q4

If an electron is moving with a velocity 600 ms–1 which is accurate upto 0.005%, then calculate the uncertainty in its position.

(h = 6.63 × 10–34 Js, mass of electron = 9.1 × 10–31 kg)

Q5

What is the transition in the hydrogen spectrum would have the same wavelength as the Balmer transition, n = 4 to n = 2 of He+ spectrum?

Q6

Calculate the energy required for the process

He+ (g) → He2+ (g) + e

The ionization energy for the H atom in the ground state is

2.18 × 10–18 J atom–1.

Q7

What is the wavelength of the light emitted when the electron in a hydrogen atom undergoes transition from an energy level with n = 4 to an energy level with n = 2? What is the colour corresponding to this wavelength? (Rydberg constant = 109,677 cm–1

Q8

A certain particle carries 2.5 × 10–16 C of static electric charge. Calculate the number of electrons present in it.

Q9

An ion with mass number 37 possesses one unit of negative charge. If the ion contains 11.1% more neutrons then the electrons, find the symbol of the ion.

Q10

An ion with mass number 56 contains 3 units of positive charge and 30.4% more neutrons than electrons. Assign the symbol to this ion.