इन्द्रधनुष कैसे बनता है?| How does a Rainbow form? | Light |Vigyan Class 10| Doubtnut | Ruchi Mam

(i) In how many ways a committee of 4 members out of 5 gents and 6 ladies can be formed if there is at least one lady in the committee? (ii) From a class of 12 boys and 8 girls, 10 students are to be chosen for a competition, including at least 4 boys and 4 girls. The two boys whho won the prizes last year should be included. In how many was can this selection be made?

How many photons per second does a one watt bulb emit if its efficiency is 10% and the wavelength of light emitted is 500 nm

The blinking time of an eye is equal to 30mus . What is the speed of light in metres per blink? How far does light travel in one blink? Assume the speed of light in vacuum is 3xx10^(8)ms^(-1) .

The average distance between the surface of the Earth and the surface of the Sun is 1.49xx10^(11) m. How much time in minutes does it take for light leaving the surface of the Sun to reach the Earth ?

Answer the following questions (a) In a single slit diffraction experiment, the width of the slit is made double the original width. How does this affect the size and intensity of the central diffraction band? (b) In what way is diffraction from each slit related to the interference pattern in a double-slit experiment? (c) When a tiny circular obstacle is placed in the path of light from a distant source, a bright spot is seen at the centre of the shadow of the obstacle. Explain why? (d) Two students are separated by a 7 m partition wall in a room 10 m high. If both light and sound waves can bend around obstacles, how is it that the students are unable to see each other even though they can converse easily (e) Ray optics is based on the assumption that light travels in a straight line. Diffraction effects (observed when light propagates through small apertures/slits or around small obstacles) disprove this assumption. Yet the ray optics assumption is so commonly used in understanding location and several other properties of images in optical instruments. What is the justification?

Although this text speaks of factual events and situations of misery it transforms these situations with an almost poetical prose into a literary experience. How does it do so? Here are some literary devices: Hyperbole is a way of speaking or writing that makes something sound better or more exciting than it really is. For example: Garbage to them is gold. A Metaphor, as you may know, compares two things or ideas that are not very similar. A metaphor describes a thing in terms of a single quality or feature of some other thing, we can say that a metaphor "transfers" a quality of one thing to another. For example: The road was a ribbon of light. Simile is a word or phrase that compares one thing with another using the words "like" or "as". For example: As white as snow. Carefully read the following phrases and sentences taken from the text. Can you identify the literary device in each example? 10. And survival in Seemapuri means rag-picking. Through the years, it has acquired the proportions of a fine art.