Question

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Answer 1

Answer:

Explanation:

17.)The Tyndall effect is the phenomenon in which the particles in a colloid scatter the beams of light that are directed at them. This effect is exhibited by all colloidal solutions and some very fine suspensions. Therefore, it can be used to verify if a given solution is a colloid. The intensity of scattered light depends on the density of the colloidal particles as well as the frequency of the incident light.

18.)The sky appears dark instead of blue to an astronaut because there is no atmosphere in the outer space that can scatter the sunlight. As the sunlight is not scattered, no scattered light reach the eyes of the astronauts and the sky appears black to them.

19 .)a.) see in pic -1

 b.) see in pic -2

20

a.)resistance in parallel=r1×r2×r3/r1+r2+r3

b.)resistance:

Resistance is the property of a conductor, which determines the quantity of current that passes through it when a potential difference is applied across it.  

A resistor is a electrical componet with a predetermined electrical resistance, like 1 ohm, 10 ohms 100 ohms 10000 ohms etc.

resistors:

Depending on how much current you want to pass through a circuit, you would design the circuit with the required resistors.

When it comes actual circuit designing, dealing with components or physical board designing, these two words become interchangeable .For example, if we say "a resistor of 22 ohms" or we say "a resistance of 22 ohms", both are accpetable.

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finished

i mentioned questions

and both pic are of 19th question

Answer 2

Answer:

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1) Tyndall effect, also called Tyndall phenomenon, scattering of a beam of light by a medium containing small suspended particles—e.g., smoke or dust in a room, which makes visible a light beam entering a window. The effect is named for the 19th-century British physicist John Tyndall, who first studied it extensively.

2) In the image...

3) In the image...

4) A concave lens is thinner in the middle and thicker at the edges. A convex lens is thicker in the middle and thinner at the edges. Used in the camera, focus sunlight, overhead projector, projector microscope, simple telescope, magnifying glasses, etc. It is also used for the correction of the problem in long sight.

5) If Rp be equal resistance of parallel combination then laws of resistance in parallel.

• Voltage across each resistor is same and is equal to the applied voltage
• Total current = sum of the currents through the individual resistance.

6) Resistance is defined as the property of the conductor which opposes the flow of electric current. It is also defined as the ratio of the voltage applied to the electric current flowing through it. The resistance of a conductor depends on the length, area of cross-section, and the nature of the material that is used in the manufacturing of the conductor. For a conductor, the resistance is directly proportional to the length of the conductor and inversely proportional to the area of cross-section.

Resistivity is defined as the resistance offered by the material per unit length for unit cross-section. The SI unit of resistivity is Ohm.meter. Resistivity increases linearly with temperature. The resistivity of conductors is low when compared to the resistivity of the insulators. Therefore, it can be represented as:

Resistivity of conductors < Resistivity of alloys < Resistivity of insulators.