Malleable: Malleable means elements when beaten turn into thin sheets called malleable. For example, gold has a maximum tendency of being malleable. Ductile: Elements having a tendency that they can be drawn into thin wires the tendency is called ductile. For example, gold has a maximum tendency ofRead more
Malleable: Malleable means elements when beaten turn into thin sheets called malleable. For example, gold has a maximum tendency of being malleable.
Ductile: Elements having a tendency that they can be drawn into thin wires the tendency is called ductile. For example, gold has a maximum tendency of ductility.
(i) Mercury is the metal which is liquid at room temperature. (ii) Sodium & Potassium are the metals that can be cut with a knife. (iii) Silver is the metal which is the best conductor of heat. (iv) Lead and Mercury are the metal that are poor conductors of heat.
(i) Mercury is the metal which is liquid at room temperature.
(ii) Sodium & Potassium are the metals that can be cut with a knife.
(iii) Silver is the metal which is the best conductor of heat.
(iv) Lead and Mercury are the metal that are poor conductors of heat.
(c) The action of ciliary muscles holding the eye lens changes the focal length of eye lens enabling the eye to focus the image of objects at varying distances.
(c) The action of ciliary muscles holding the eye lens changes the focal length of eye lens enabling the eye to focus the image of objects at varying distances.
For a normal eye, image distance in the eye is fixed and is equal to the distance of retina from the eye lens. When we increase the distance of the object from the eye, focal length of eye lens is changed on account of accommodating power of the eye so as to keep image distance constant.
For a normal eye, image distance in the eye is fixed and is equal to the distance of retina from the eye lens. When we increase the distance of the object from the eye, focal length of eye lens is changed on account of accommodating power of the eye so as to keep image distance constant.
Due to wind and convection currents, density of the atmospheric layers keeps on change. As a result, the position of a star keeps fluctuating from its mean position. This fluctuating image of the stars makes them appear twinkling to the observer.
Due to wind and convection currents, density of the atmospheric layers keeps on change. As a result, the position of a star keeps fluctuating from its mean position. This fluctuating image of the stars makes them appear twinkling to the observer.
Planets do not emit light. However, they become visible due to reflection of light falling on them. The planets are much closer to the earth and thus can be considered as the extended source of light. The fluctuations in the light coming from various points of the planet due to atmospheric refractioRead more
Planets do not emit light. However, they become visible due to reflection of light falling on them. The planets are much closer to the earth and thus can be considered as the extended source of light. The fluctuations in the light coming from various points of the planet due to atmospheric refraction get averaged out. As a result, no twinkling of planets is seen.
Explain the meanings of malleable and ductile.
Malleable: Malleable means elements when beaten turn into thin sheets called malleable. For example, gold has a maximum tendency of being malleable. Ductile: Elements having a tendency that they can be drawn into thin wires the tendency is called ductile. For example, gold has a maximum tendency ofRead more
Malleable: Malleable means elements when beaten turn into thin sheets called malleable. For example, gold has a maximum tendency of being malleable.
Ductile: Elements having a tendency that they can be drawn into thin wires the tendency is called ductile. For example, gold has a maximum tendency of ductility.
Give an example of a metal which
(i) Mercury is the metal which is liquid at room temperature. (ii) Sodium & Potassium are the metals that can be cut with a knife. (iii) Silver is the metal which is the best conductor of heat. (iv) Lead and Mercury are the metal that are poor conductors of heat.
(i) Mercury is the metal which is liquid at room temperature.
(ii) Sodium & Potassium are the metals that can be cut with a knife.
(iii) Silver is the metal which is the best conductor of heat.
(iv) Lead and Mercury are the metal that are poor conductors of heat.
The human eye can focus on objects at different distances by adjusting the focal length of the eye lens. This is due to
(b) The property of the eye to adjust the focal length of eye lens is called accommodation.
(b) The property of the eye to adjust the focal length of eye lens is called accommodation.
See lessThe human eye forms the image of an object at its
(d) retina
(d) retina
See lessThe least distance of distinct vision for a young adult with normal vision is
(c) The least distance of distinct vision for a young adult with normal vision is 25 cm.
(c) The least distance of distinct vision for a young adult with normal vision is 25 cm.
See lessThe change in focal length of an eye lens is caused by the action of the
(c) The action of ciliary muscles holding the eye lens changes the focal length of eye lens enabling the eye to focus the image of objects at varying distances.
(c) The action of ciliary muscles holding the eye lens changes the focal length of eye lens enabling the eye to focus the image of objects at varying distances.
See lessWhy is a normal eye not able to see clearly the objects placed closer than 25 cm?
The least distance of distinct vision for a normal eye is 25 cm. So, a normal eye will not be able to see clearly any object placed closer than 25 cm.
The least distance of distinct vision for a normal eye is 25 cm. So, a normal eye will not be able to see clearly any object placed closer than 25 cm.
See lessWhat happens to the image distance in the eye when we increase the distance of an object from the eye?
For a normal eye, image distance in the eye is fixed and is equal to the distance of retina from the eye lens. When we increase the distance of the object from the eye, focal length of eye lens is changed on account of accommodating power of the eye so as to keep image distance constant.
For a normal eye, image distance in the eye is fixed and is equal to the distance of retina from the eye lens. When we increase the distance of the object from the eye, focal length of eye lens is changed on account of accommodating power of the eye so as to keep image distance constant.
See lessWhy do stars twinkle?
Due to wind and convection currents, density of the atmospheric layers keeps on change. As a result, the position of a star keeps fluctuating from its mean position. This fluctuating image of the stars makes them appear twinkling to the observer.
Due to wind and convection currents, density of the atmospheric layers keeps on change. As a result, the position of a star keeps fluctuating from its mean position. This fluctuating image of the stars makes them appear twinkling to the observer.
See lessExplain why the planets do not twinkle.
Planets do not emit light. However, they become visible due to reflection of light falling on them. The planets are much closer to the earth and thus can be considered as the extended source of light. The fluctuations in the light coming from various points of the planet due to atmospheric refractioRead more
Planets do not emit light. However, they become visible due to reflection of light falling on them. The planets are much closer to the earth and thus can be considered as the extended source of light. The fluctuations in the light coming from various points of the planet due to atmospheric refraction get averaged out. As a result, no twinkling of planets is seen.
See less