NCERT
- The change in focal length of an eye lens is caused by the action of the (a) pupil (b) retina (c) ciliary muscles(d)iris Correct option is c) ciliary muscles 2
- The least distance of distinct vision for a young adult with normal vision is about (a) 25 m (b) 2.5 cm (c) 25 Correct option is c) 25 cm 2
- The human eye forms the image of an object at its (a) cornea (b) iris (c) pupil (d) retina Correct option is d) retina 2
- The human eye can focus objects at different distances by adjusting the focal length of the eye lens Correct option is b) accommodation 2
- A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is The student is suffering from myopia or short-sightedness. The defect can be corrected by the use of concave (diverging ) lens of an appropr... 1
- What is the far point and near point of the human eye with normal vision? The near point of the eye is the minimum distance of the object from the eye, which can be seen distinctly without strain. For a normal huma... 1
- A person with a myopic eye cannot see objects beyond 1.2 m distinctly. What should be the type of the corrective A person with a myopic eye should use a concave lens of focal length 1.2 m so as to restore proper vision. 1
- What is meant by power of accommodation of the eye? The ability of the eye lens to adjust its focal length, so as to clearly focus rays coming from distant as well a near objects on the retina... 1
- Explain the following. (a) Why is the tungsten used almost exclusively for filament of electric lamps? a) The melting point and of Tungsten is an alloy which has very high melting point and very high resistivity so does not burn easily at a hi... 2
- An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is Rate of heat produced by a device is given by the expression for power as, P= I²R Where, Resistance of the electric heater, R= 8 Ω Current d... 1
- Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes? Energy consumed by an electrical appliance is given by the expression,H= Pt Where, Power of the appliance = P Time = t Energy consumed by a... 1
- Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to electric mains supply. Both the bulbs are connected in parallel. Therefore, potential difference across each of them will be 220 V, because no division of voltage... 1
- Compare the power used in the 2 Ω resistor in each of the following circuits: (i) a 6 V battery in series with 1 Ω and 2 (i) Potential difference, V = 6 V 1 Ω and 2 Ω resistors are connected in series. Therefore, equivalent resistance of the circuit, R = 1 + 2... 1
- A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance https://www.youtube.com/watch?v=Ru4TReFRK7A&ab_channel=Darshanclasses 2
- Several electric bulbs designed to be used on a 220 V electric supply line, are rated 10 W. How many lamps can Resistance R₁ of the bulb is given by the expression, Supply voltage, V = 220 V Maximum allowable current, I = 5 A Rating of an electric bul... 2
- Show how you would connect three resistors, each of resistance 6 Ω, so that the combination has a resistance of https://youtu.be/LggubtJYvrU 2
- How many 176 Ω resistors (in parallel) are required to carry 5 A on a 220 V line? For x number of resistors of resistance 176 Ω, the equivalent resistance of the resistors connected in parallel is given by Ohm's law asV= I... 1
- A battery of 9 V is connected in series with resistors of 0.2 Ω, 0.3 Ω, 0.4 Ω, 0.5 Ω and 12 Ω, respectively There is no current division occurring in a series circuit. Current flow through the component is the same, given by Ohm’s law as V= IR I= V... 1
- When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Resistance (R) of a resistor is given by Ohm's law as,V= IR R= V/I Where, Potential difference, V= 12 V Current in the circuit, I= 2.5 mA =... 1
- A copper wire has diameter 0.5 mm and resistivity of 1.6 × 10−8 Ω m. What will be the length of this wire to make https://youtu.be/gdC4O4SbCAg 2
- How is a voltmeter connected in the circuit to measure the potential difference between two points? To measure the potential difference between two points, a voltmeter should be connected in parallel to the points. 1
- Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and Correct option is c) 1:4 2
- An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be - (a) 100 W Correct option is d) 25 W 2
- Which of the following terms does not represent electrical power in a circuit? (a) I2R (b) IR2 (c) VI (d) V2/R Correct option is b) IR² 2