Tag: physics

Metals reflect incident light by the vibrations of free electrons under the influence of electric field of incident wave. The conductivity of metals decreases with increase of temperature due to increase in random motion of free electrons. The bonding is therefore metallic.

LEDs are better than conventional incandescent power lamps because:-

A laser device produces amplification in the Ultraviolet or visible region of the spectrum. 

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term "laser" originated as an acronym for "light amplification by stimulated emission of radiation".

According to heating effect of electric current, heat is produced in the materials that have resistance, thus electric immersion water heater, electric iron box and electric fuse are the applications of heating effect of electric current.

Bulbs are filled with chemically inactive Nitrogen or Argon gas to prevent the oxidation of tungsten filament used in the bulb.

An electric fuse in households works on the principle of Joule's heating that heat produced due to the excess current flowing through it melts the fuse wire which cut off the circuit and hence the appliance is prevented from damage.

For constant electric power, higher the voltage, lower is the current (as $P=IV$) through the wire. As power loss due to Joule's heating is proportional to $I^2$, for a small current, power loss is also small. So, power is transmitted over long distances at high voltage to minimize power loses due to Joule's heating.

Using Right-Hand thumb rule and (Flemmings Left Hand Rule, current direction (i) = Left Side Magnetic field  (B) = outwards, so the direction of the force is upwards.

When a metallic conductor is heated its atoms get more energy and get agitated. That is why they vibrate with greater amplitude and frequency.