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Consider the following statements.<br>An ordinary light bulb has a rather short life because the<br>1. Filament wire is not uniform.<br>2. Bulb cannot be evacuated completely.<br>3. Wires supporting the filament melt at high temperatures.<br>Which of the above statements are correct?

Correct Answer: 1, 2 and 3

Molten steel is kept in a ladle. Due in natural convection. mixing occurs inside the melt. A 1cm diameter sphere is held in the centre of the melt where the steel flows upward. so as to measure the force exerted by the melt on the sphere. The force. F exerted by the melt on the sphere is given by $$F = f\left( {\frac{\pi }{8}} \right).\left( {\frac{{{\mu ^2}}}{8}} \right){\left( {\operatorname{Re} } \right)^2}.$$
Data: Density of liquid steels
= 7100 kg. m-3
Viscosity of liquid steel
= 6.5 × 10-3 kg. m-1. s-1
Reynolds number (Re) of the melt
= 5 × 103
Friction factor (f) = 0.3
The velocity of melt (m.s-1) in the central portion of the ladle would be

A 100 W light bulb has a tungsten filament (emissivity = 0.30) which is required to operate at 2780 K. If the bulb is completely evacuated, calculate the minimum surface area of the tungsten filament

Melt spinning of polymers involves the forcing of polymer melt through spinnerettes (fine holes) into an atmosphere kept at a temperature lower than the melting point of the polymer, which causes the fine diameter polymer melt to harden into filaments. Melt spinning is not used in case of the __________ fibres.

An elevator is assembled to raise equipment to a height of 22m. It is estimated that maximum weight of the material to be raised is 4.9kN. It is observed acceleration in such cases is 1.2m/s².10mm diameter wire ropes with fibre core are used. The tensile designation of the wire is 1500.Number of rope wires is assumed to be 2. Number of rope wires is assumed to be 2. Calculate the weight of wire if weight of 50m wire is 18kg. Calculate the force due to acceleration.

An elevator is assembled to raise equipment to a height of 22m. It is estimated that maximum weight of the material to be raised is 4.9kN. It is observed acceleration in such cases is 1.2m/s².10mm diameter wire ropes with fibre core are used. The tensile designation of the wire is 1500.Number of rope wires is assumed to be 2. Number of rope wires is assumed to be 2. Calculate the total load on wire rope neglecting the bending load if weight of 50m wire is 18kg.

Consider the following statements about visible light, UV light and X-ray.
1. The wavelength of visible light is more than that of X-ray.
2. The energy of X-ray photons is higher than that of UV light photons.
3. The energy of UV light photons is less than that of visible light photons.
Which of the statement(s) given above is/are correct?

A telephone switchboard 100 pair cable can be made up with either enameled wire or tinned wire. There will be 400 soldered connections. The cost of soldering a connection on the enameled wire will be P 1.65 on the tinned wire, it will be P 1.15. A 100- pair cable made up with enameled wire cost P 0.55 per linear foot and those made up of tinned wire cost P 0.75 per linear foot. Determine the length of cable run in feet so that the cost of each installation would be the same.

Read the following passage carefully and choose the most appropriate answer to the question out of the four alternatives.
The human eye is a complex part of the body that is used for seeing. Eyes enable people to perform daily tasks and to learn about the world that surrounds them. Sight, or vision, is a rapidly occurring process that involves continuous interaction between the eye, the nervous system, and the brain. When someone looks at an object, what he really sees is the light reflected from the object. This reflected light passes through the lens and falls on the retina of the eye. Here the light induces nerve impulses that travel through the optic nerve to the brain and then over other nerves to muscles and glands.
The eye is similar to a television camera. Both the eye and the television camera convert light energy to electrical energy. The eye converts light to nerve impulses that are interpreted by the brain as the sense perception called sight. A television camera converts light to electronic signals that are broadcast and transformed into light images in a television receiver. It is wonderful that human eyes blink an average of once every six seconds. This washes the eye with the salty secretion from the tear or lachrymal glands. Each tear gland is about the size and shape of an almond. These glands are situated behind the upper eyelid at the outer corner of the eye. After passing over the eye, the liquid from the gland is drained into the nose through the tear duct at the inner corner of the eye. The sense perception that the brain releases after the eye converts light to nerve impulses is known as

Read the following passage carefully and choose the most appropriate answer to the question out of the four alternatives.
The human eye is a complex part of the body that is used for seeing. Eyes enable people to perform daily tasks and to learn about the world that surrounds them. Sight, or vision, is a rapidly occurring process that involves continuous interaction between the eye, the nervous system, and the brain. When someone looks at an object, what he really sees is the light reflected from the object. This reflected light passes through the lens and falls on the retina of the eye. Here the light induces nerve impulses that travel through the optic nerve to the brain and then over other nerves to muscles and glands.
The eye is similar to a television camera. Both the eye and the television camera convert light energy to electrical energy. The eye converts light to nerve impulses that are interpreted by the brain as the sense perception called sight. A television camera converts light to electronic signals that are broadcast and transformed into light images in a television receiver. It is wonderful that human eyes blink an average of once every six seconds. This washes the eye with the salty secretion from the tear or lachrymal glands. Each tear gland is about the size and shape of an almond. These glands are situated behind the upper eyelid at the outer corner of the eye. After passing over the eye, the liquid from the gland is drained into the nose through the tear duct at the inner corner of the eye. The eye is similar to the television camera because both

Two metallic wires made from copper have same length but the radius of wire 1 is half of that of wire 2. The resistance of wire 1 is R. If both the wires are joined together in series, the total resistance becomes