Explanation

• A lake starts freezing because of the cold atmosphere. It will first freeze At the top surface
• ***
• concept:
• when the water freezes to ice, the ice becomes significantly less dense than the water and continues to float on the lake's surface.
• Below 4° Celsius, water becomes less dense as it gets colder, causing water to freeze to float to the top.
  
  

Explanation

The phenomenon of refraction of light is the shift in the path of light as it travels from one medium to another

Explanation

The guitar is a musical instrument of the chordophone family.

The standard guitar has following six strings:

1. E

2. A

3. D

4. G

5. B

6. E

Explanation

A galvanometer is an instrument that can detect and measure small amounts of current in an electrical circuit

Explanation

• Photovoltaic (PV) cells convert solar energy into electricity through a physical and chemical phenomenon known as the photovoltaic effect.
• Photovoltaic cells are also called solar cells.
• They convert light energy from the Sun directly into electrical energy.

Explanation

Ole Rømer, an astronomer from Denmark made the first quantitative measurements of the speed of light in 1676.

Explanation

• The great red Spot is a hurricane in Jupiter's southern hemisphere with purple-colored clouds that spin counterclockwise at wind speeds that exceed those in any hurricane on the earth.
• The excellent purple Spot has slowly changed over time, and is presently about 1.3 instances as huge as our planet.
  

Explanation

The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium.

Explanation

Short-sightedness is caused due to elongation of the eyeball

 It also may result when the curve of the cornea is too steep. 

The messages sent from the retina to the brain are perceived as blurry

Explanation

Oximeter is used to measure the oxygen level in blood & heart rate. 

Pulse oximeters can be attached to your fingers, forehead, nose, foot, ears or toes.

The device may then be reused or disposed of.