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Principal focus of a concave mirror is a point on the principal axis where all rays that are straight and parallel to the principal axis appear to diverge from after reflection by the concave mirror.
Andreaz answered the question on January 12, 2018 at 20:48
- How does the distance between the interference fringes and the separation distance of the slits relate?(Solved)
How does the distance between the interference fringes and the separation distance of the slits relate?
Date posted: January 8, 2018. Answers (1)
- Can visible light produce interference fringes? Explain(Solved)
Can visible light produce interference fringes? Explain
Date posted: January 8, 2018. Answers (1)
- Briefly explain how unpolarized light and plane polarized lights can be distinguished(Solved)
Briefly explain how unpolarized light and plane polarized lights can be distinguished.
Date posted: January 8, 2018. Answers (1)
- A student makes a loud sound and hears the echo of the sound after 2.0s. If the speed of sound in air is 330.5m/s, calculate...(Solved)
A student makes a loud sound and hears the echo of the sound after 2.0s. If the speed of sound in air is 330.5m/s, calculate the distance between the student and the object causing the echo.
Date posted: January 7, 2018. Answers (1)
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What do you understand by the term e.m.f of a cell?
Date posted: January 7, 2018. Answers (1)
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Is it safe to stay in a car during a lightning storm? Explain.
Date posted: January 7, 2018. Answers (1)
- (i) State Snell’s law of refraction of light (ii) Give two advantages of totally internally reflecting prisms over plane...(Solved)
(i) State Snell’s law of refraction of light
(ii) Give two advantages of totally internally reflecting prisms over plane mirrors.
Date posted: January 7, 2018. Answers (1)
- A form 4 student observed that his grandfather positions a book far from his eyes when reading it. Explain the type of lenses that the...(Solved)
A form 4 student observed that his grandfather positions a book far from his eyes when reading it. Explain the type of lenses that the student should advice his grandfather to wear.
Date posted: January 7, 2018. Answers (1)
- When a new dry cell is connected in series with a 2.7 ohms resistor, a current of 0.5A flows in the circuit. Determine the internal resistance...(Solved)
When a new dry cell is connected in series with a 2.7 ohms resistor, a current of 0.5A flows in the circuit. Determine the internal resistance of the cell.
Date posted: January 7, 2018. Answers (1)
- Why does a gun recoil when it is fired ?(Solved)
Why does a gun recoil when it is fired ?
Date posted: January 7, 2018. Answers (1)
- Water flows along a horizontal pipe of cross-section area 35^2 cm and constriction of cross section 5^2 cm . if the speed of water...(Solved)
Water flows along a horizontal pipe of cross-section area 35^2 cm and constriction of cross section 5^2 cm . if the speed of water at the construction is 2 m/s
Calculate:
i)Continuity constant in SI unit
ii) the speed in the wide section
Date posted: January 7, 2018. Answers (1)
- A boy heats 5kg of water to a temperature of 80oC. When she adds m kg of water at 15oC the mixture attains a...(Solved)
A boy heats 5kg of water to a temperature of 80oC. When she adds m kg of water at 15oC the mixture attains a temperature of 40oC. Determine the value of m
Date posted: January 7, 2018. Answers (1)
- Define an echo(Solved)
Define an echo.
Date posted: January 6, 2018. Answers (1)
- State the difference between lens of a camera and that of an eye.(Solved)
State the difference between lens of a camera and that of an eye.
Date posted: January 6, 2018. Answers (1)
- (i) State the reason why a lamp is made of tungsten. (ii) Why is the bulb of such a lamp filled with an active gas?(Solved)
(i) State the reason why a lamp is made of tungsten.
(ii) Why is the bulb of such a lamp filled with an active gas?
Date posted: January 6, 2018. Answers (1)
- A hockey player trains on a nylon fiber surface. As he runs around, his shoes rub against the surface and he becomes positively charged.(Solved)
A hockey player trains on a nylon fiber surface. As he runs around, his shoes rub against the surface and he becomes positively charged.
(i) Explain in terms of particles involved, how he becomes positively charged.
Date posted: January 6, 2018. Answers (1)
- State the advantages of solid state devices over vacuum tubes(Solved)
State the advantages of solid state devices over vacuum tubes.
Date posted: January 6, 2018. Answers (1)
- (a) What is diffusion? (b) A smoke cell contains a mixture of trapped air and smoke. The cell is brightly lit and viewed through a microscope. State...(Solved)
(a) What is diffusion?
(b) A smoke cell contains a mixture of trapped air and smoke. The cell is brightly lit and viewed through a microscope. State and explain what is observed.
(c) A beaker is filled completely with water. A spoon full of common salt is added slowly. The salt dissolves and the water does not overflow.
(i) Why is salt added slowly?
(ii) Why doesn't the water overflow?
Date posted: January 5, 2018. Answers (1)
- A stream of air passing over a roof of room at higher velocity than the velocity of air inside the room is likely to...(Solved)
A stream of air passing over a roof of room at higher velocity than the velocity of air inside the room is likely to blow off the roof. Give a reason for this
Date posted: January 5, 2018. Answers (1)
- Explain why in trying to move a rigid wall, a person is said to be doing no work at all.(Solved)
Explain why in trying to move a rigid wall, a person is said to be doing no work at all.
Date posted: January 3, 2018. Answers (1)