In Fleming’s left hand rule, the finger that indicates the direction of the electric current is
a.
thumb
b.
index finger
c.
middle finger
Correct Answer
d.
little finger
Step-by-Step AI Explanation
Verified Method
According to Fleming's left-hand rule: the thumb indicates the direction of the force (motion) on the conductor, the index finger indicates the direction of the magnetic field, and the middle finger indicates the direction of the electric current.
Q2mcq1 mark
If a device of $840W$ is to be used with $220V$ potential difference, then the rate of the fuse that is to be connected in this electrical circuit is
a.
2A
b.
4A
Correct Answer
c.
8A
d.
12A
Step-by-Step AI Explanation
Verified Method
The power $P = 840 W$ and voltage $V = 220 V$. Using the formula $P = VI$, the current $I = P / V = 840 / 220 \approx 3.82 A$. Since the fuse rating must be slightly higher than the operating current to prevent nuisance tripping, a 4A fuse is the appropriate choice.
Q3mcq1 mark
Observe the diagrams given below : The correct conclusion that you can draw here is that, the angle of deviation will be
a.
maximum in Q
Correct Answer
b.
minimum in P
c.
more in P than in Q
d.
more in R than in Q
Step-by-Step AI Explanation
Verified Method
The angle of deviation is inversely proportional to the wavelength of the light. Among blue, green, and yellow light, blue light has the shortest wavelength and thus undergoes the maximum deviation through a glass prism. Since Q represents the blue light ray, the angle of deviation is maximum in Q.
Q4short answer1 mark
Draw the symbol of ‘variable resistance’ or ‘Rheostat’ used in the electric circuit.
Step-by-Step AI Explanation
Verified Method
The symbol for a rheostat (variable resistance) is typically drawn as a resistor symbol with an arrow pointing across it, or an arrow pointing to the middle of the resistor symbol.
Q5short answer1 mark
Among the two types of particles ‘A’ and ‘B’ in the atmosphere, particles ‘A’ scatter mainly the blue light and particles ‘B’ scatter mainly the red light. Which type of the particles have larger size ?
Step-by-Step AI Explanation
Verified Method
Particles 'B' have a larger size. Rayleigh scattering explains that shorter wavelengths are scattered by smaller particles (like air molecules scattering blue light), while larger particles (like dust or water droplets) scatter longer wavelengths, such as red light.
Q6short answer2 marks
Write any four properties of magnetic field lines.
Step-by-Step AI Explanation
Verified Method
1. Magnetic field lines emerge from the north pole and merge into the south pole. 2. They are closed, continuous curves. 3. The field lines never intersect each other. 4. The relative strength of the magnetic field is shown by the degree of closeness of the field lines (denser lines mean a stronger field).
Q7short answer2 marks
Explain the working of earth wire in the domestic electric circuit.
Step-by-Step AI Explanation
Verified Method
The earth wire is connected to a metal plate deep in the earth near the house. Its purpose is to provide a low-resistance conducting path for any leakage of current. If a live wire touches the metallic body of an appliance, the leakage current flows to the earth, preventing an electric shock to the user and triggering the fuse or circuit breaker to cut off the power supply.
Q8short answer
a) What happens if the electric current is increased in a solenoid ?
Step-by-Step AI Explanation
Verified Method
If the electric current in a solenoid is increased, the strength of the magnetic field produced inside and around the solenoid also increases proportionally.
Q8short answer3 marks
What is myopia ( near sightedness ) ? Write any two causes for this defect. How can this defect of the eye be corrected ?
Step-by-Step AI Explanation
Verified Method
Myopia, or near-sightedness, is a defect of vision in which a person can see nearby objects clearly but cannot see distant objects distinctly. The image of a distant object is formed in front of the retina rather than on it.
Causes of myopia:
1. Excessive curvature of the eye lens.
2. Elongation of the eyeball.
Correction: This defect can be corrected by using a concave lens (diverging lens) of appropriate focal length, which shifts the image back onto the retina.
Q9short answer
b) What happens to the soft iron rod when it is placed inside the solenoid carrying electric current ?
Step-by-Step AI Explanation
Verified Method
When a soft iron rod is placed inside a solenoid carrying an electric current, it gets magnetized and behaves like an electromagnet as long as the current flows through the solenoid.
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Draw the ray diagram showing the formation of image by a convex lens when the object is placed in front of the lens beyond $2F_1$. ($F_1$ : Principal focus of the lens )
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A wire of length ‘l’ and area of cross-section ‘A’ has resistance of $2 \Omega$. What is the resistance of another wire of same material having length ‘2l’ and area of cross-section ‘A/2’ ?
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a) State Joule’s law of heating effect. Write its mathematical form.
b) Write any two differences between series combination of resistors and parallel combination of resistors in an electric circuit.
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a) Write any four uses of concave mirror.
b) What is magnification? If the value of magnification of an image is $+3.0$, then mention the size and nature of the image.
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a) Give reason:
i) Tungsten is used as the filament of an electric bulb.
ii) Electric filament bulbs are usually filled with nitrogen gas.
b) Write the use of an ammeter and a voltmeter. How are they connected in an electric circuit?
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10 ml of an acidic solution is added to a beaker containing 50 ml of water. What change takes place in the concentration of hydronium ions of that solution?
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Translate the following statement into chemical equation and then balance it. ‘Hydrogen gas combines with chlorine gas to form hydrogen chloride.’
OR
Balance the following chemical equations:
a) $\text{CH}_4 + \text{O}_2 \to \text{CO}_2 + \text{H}_2\text{O}$
b) $\text{Pb}(\text{NO}_3)_2 \to 2\text{PbO} + \text{NO}_2 + \text{O}_2$
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a) Write the differences between saturated hydrocarbons and unsaturated hydrocarbons.
b) Write the structural formula of propane.
OR
a) Explain the mechanism of cleaning action of soaps.
b) Carbon does not form $\text{C}^{-4}$ anion. Why?
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When a salt ‘X’ that is used to remove permanent hardness of water reacts with hydrochloric acid, the gas ‘Y’ releases. Later the gas ‘Y’ is passed through lime water to produce a white precipitate ‘Z’. Then name ‘X’, ‘Y’ and ‘Z’.
OR
When the brine solution is subjected to electrolysis, name the compound formed and the gases released at the cathode and the anode. Write one use of each product.
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a) Show the formation of magnesium chloride by the transfer of electrons.
b) Give reason:
i) Aluminium oxide is called amphoteric oxide.
ii) Copper articles exposed to air for a long time gain green coat.
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a) Write the events that occur during the process of photosynthesis. In what form the carbohydrates not used immediately are stored in plants ?
b) Write the functions of stomata.
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A tall pea plant bearing round seeds (TTRR) is crossed with dwarf pea plant bearing wrinkled seeds (ttrr).
i) Write the type of plants obtained in $F_1$ generation.
ii) With the help of checker board represent the plants of $F_2$ generation obtained by the self pollination of $F_1$ plants.
iii) Write the ratio of different plants obtained in $F_2$ generation.
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a) Write the functions of the following hormones :
i) Insulin
ii) Adrenaline.
b) The leaves of chui-mui (touch-me-not) plant fold up when this plant is being touched. How does this response take place ? Explain.
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