CBSE ADDA

Sadhana Devi Vidyapith Assignment SA-1 +  Chapter: Magnetic Effects of Electric Current                                               Section-A [1-marks] 1. What does the direction of thumb indicate in the right-hand thumb rule? 2. What is the frequency of alternating current in India? 3. How will you use a solenoid to magnetize a steel bar? 4. An alternating electric current has a frequency of 50 Hz. How many times does it change its direction in one second? 5. Name devices which produce: (i) alternating current, (ii) direct current. 6. Name the physicist who discovered the magnetic effect of the electric current. 7. A straight copper conductor is held parallel to the axis of a freely suspended magnetic needle such that the conductor is under the needle and the current is flowing from south to north. In which direction the north of magnetic needle will move? 8. If a copper conductor carrying a current is held in north-south direction, in which direction will its magn

Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem? Removal of all the organisms of a trophic level will affect the entire ecosystem of that area. Its impact on different trophic levels will be different because of the organisms of a trophic level are directly dependent on them while the organisms of other trophic level are indirectly depend on them for their food. For example, killing of herbivores will increase the number of carnivores and killing of carnivores will increase the number of herbivores. Most of the organisms will die of starvation. How do flows of energy occur in tropic level? Energy is used and conveyed from one trophic level to another is a food chain. This is called flow of energy. Green plants capture about 1% of the solar energy during photosynthesis. A part of this trapped energy is used by plants in perform

Gist of Lesson for Quick Revision (By JSUNIL) 1. An eye is the most important organ of the human body. It is associated with vision and acts as a vital optical instrument. 2. An eye is spherical in shape of about 2.3 cm diameter and is covered externally by a hard thick and opaque layer called Sclerotica. The outermost layer of the eye is sclerotic that  protects  and holds the eye. 3. Cornea is transparent part bulging out of eye and allows the light to enter in the eye. Cornea is also known as the window or aperture of the eye. 4. Iris is a circular diaphragm having a hole in its centre .this hole is called pupil 5. Iris has muscles and coloured pigments that provide different colour y eyes 6. Iris controls the amount of light entering the eye through the pupil. 7. The pupil becomes small when bright light falls on the eye. However, it becomes wide when there is dim light. 8. The eye lens is a crystalline convex lens made up of transparent and flexible tissu

1. In our country, there are attempts to increase the height of several existing dams like Tehri and Almati, dams across Narmada. What are the reasons behind it? Ans. Dams are large water storing bodies that are usually built by government agencies across the rivers to regulate the flow of water and generate electricity. They store huge amount of water for irrigation of fields throughout the year. 2. On the banks of the river, there are several factories that are discharging effluents into the river. The pH of water sample collected from the river is found to be acidic in the range of 3.5–4.5. Name the effluents which is the most likely to cause the lowering of pH of river water. What should be the effect of pollution on the fishes of the river . Ans. Untreated sewage, garbage, some human activities like bathing, washing of clothes and immersion of ashes or unburnt corpses are the most likely causes of lowering of pH of river water. It makes the water toxic and kills the aquatic o

1. In our country, there are attempts to increase the height of several existing dams like Tehri and Almati, dams across Narmada. What are the reasons behind it? Ans. Dams are large water storing bodies that are usually built by government agencies across the rivers to regulate the flow of water and generate electricity. They store huge amount of water for irrigation of fields throughout the year. 2. On the banks of the river, there are several factories that are discharging effluents into the river. The pH of water sample collected from the river is found to be acidic in the range of 3.5–4.5. Name the effluents which is the most likely to cause the lowering of pH of river water. What should be the effect of pollution on the fishes of the river. Ans. Untreated sewage, garbage, some human activities like bathing, washing of clothes and immersion of ashes or unburnt corpses are the most likely causes of lowering of pH of river water. It makes the water toxic and kills the aquatic

  Class X NCERT Solution, MCQ's Study Notes, Q & A  Chapter 10 – Light - Reflection and Refraction Q.1.Why does a light ray incident on a rectangular glass slab immersed in any medium emerge parallel to itself? Ans: The extent of bending of the ray of light at the opposite parallel faces AB (air-glass interface) and CD (glass-air interface) of the rectangular glass slab is equal and opposite. This is why the ray emerges parallel to the incident ray.      OR, (The glass slab is rectangular and both sides of the glass slab have the same medium. The light refracts in such a way that incident and emergent rays are parallel.) Q.2.An object is placed at a distance of 10cm from a convex mirror of focal length of 15cm . Find the position and nature of the image Solution: Given :   f = +15cm          u = -10cm        v = ?’ 1/ f = 1/u +1/v   1/15 = -1/10 + 1/v 1/15 + 1/10 = 1/v 1/v = 1/6       v = 6cm Position of the image: Since V is formed at a distance o