A hydrogen atom moving at a speed v absorbs a photon of wavelength 122 nm and stops. Find the value of v. Mass of a hydrogen atom = ` 1.67 xx 10^-27kg`.

Explanation

To solve the problem, we will use the principle of conservation of momentum. Here are the steps to find the value of \( v \):

### Step 1: Understand the scenario
A hydrogen atom is moving with an initial speed \( v \) and absorbs a photon of wavelength \( 122 \, \text{nm} \). After absorbing the photon, the hydrogen atom comes to a stop, meaning its final velocity is \( 0 \).

### Step 2: Write the conservation of momentum equation
According to the conservation of momentum, the initial momentum of the hydrogen atom must equal the momentum of the photon it absorbs. Since the atom stops after absorbing the photon, we can write:

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