**What is the power of one laser pulse?****During the very brief time of the pulse, what is the intensity of the light wave?**

The **question aims to find the power** of one laser pulse and the** intensity of the light**.** Ratio of amount of energy transferred or converted per unit of time is called Power**. In the International System of Units, the power unit is the watt, which is equal to one joule per second. In older works, power is also sometimes called activity. **Power is a scalar quantity**. Power is also related to other quantities as well; **for example,** the power involved in moving a ground car is the product of the traction force on the wheels and the vehicle’s velocity. **Output power of a motor is product of the engine’s torque and the angular velocity of its output shaft**. Similarly, the energy dissipated in an electrical element of a circuit is the product of the current flowing through the element and the voltage across that element.

**Power is the speed concerning the time in which work is done; it is the time derivative of work:**

\[P=\dfrac{dW}{dt}\]

In **content of physics**, the **intensity or flux of radiant energy is the power transferred per unit area**, where the area is measured in a plane perpendicular to the energy’s propagation direction. In the SI system, it has **units of watts per square meter** $(\dfrac{W}{m^{2}})$.

**Expert Answer**

**Part(a)**

The **power will be the ratio of the energy of emitted over the time during which energy was emitted.**

\[P=\dfrac{E}{t}\]

\[P=\dfrac{1.10^{-3}}{1.5.10^{-8}}\]

\[P=66.7kW\]

**Part (b)**

The** intensity is equal to power over the area.**

\[I=\dfrac{P}{A}\]

\[I=\dfrac{4P}{\pi d^{2}}=\dfrac{4.66700}{\pi.0.001^{2}}\]

\[I=8.5.10^{10}\dfrac{W}{m^{2}}\]

**Numerical Result**

The **power of one laser pulse** is calculated as:

\[P=66.7kW\]

The **intensity of the light wave** is calculated as:

\[I=8.5.10^{10}\dfrac{W}{m^{2}}\]

**Example**

LASIK eye surgery uses the pulses of the laser light to shave tissue from the cornea and reshape it. A typical LASIK laser emits a $1.0\:mm$ diameter laser beam with a wavelength of 193 nm. Each laser pulse lasts $20\:ns$ and contains $1.0\: mJ$ of light energy.

**– What is the power of one laser pulse?**

**– During the very brief time of the pulse, what is the intensity of the light wave?**

**Solution**

**Part(a)**

The **power will be the ratio of the energy of emitted over the time during which energy was emitted.**

\[P=\dfrac{E}{t}\]

\[P=\dfrac{2.10^{-3}}{2.10^{-8}}\]

\[P=50kW\]

**Part (b)**

The** intensity is equal to power over the area.**

\[I=\dfrac{P}{A}\]

\[I=\dfrac{4P}{\pi d^{2}}=\dfrac{4.50000}{\pi.0.001^{2}}\]

\[I=6.366.10^{10}\dfrac{W}{m^{2}}\]

The **power of one laser pulse** is calculated as:

\[P=50kW\]

The **intensity of the light wave** is calculated as:

\[I=6.366.10^{10}\dfrac{W}{m^{2}}\]