A device that converts electrical energy into mechanical energy is
a.
Electric generator
b.
Electric motor
Correct Answer
c.
Galvanometer
d.
Voltmeter
Step-by-Step AI Explanation
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The correct choice is B. An electric motor converts electrical energy into mechanical energy. A generator does the reverse (mechanical to electrical). A galvanometer detects the presence of current, and a voltmeter measures potential difference.
Q2mcq1 mark
A mirror forms an erect and enlarged image of an object. Then the type of the mirror and the nature of the image respectively are
a.
convex mirror and virtual image
b.
concave mirror and real image
c.
plane mirror and real image
d.
concave mirror and virtual image
Correct Answer
Step-by-Step AI Explanation
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The correct choice is D. A concave mirror produces an enlarged, erect, and virtual image when the object is placed between the pole (P) and the principal focus (F). Convex and plane mirrors cannot form enlarged images of real objects.
Q3mcq1 mark
The power plant that generates electricity without using the turbines is
a.
Thermal power plant
b.
Hydro power plant
c.
Solar power plant
Correct Answer
d.
Nuclear power plant
Step-by-Step AI Explanation
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The correct choice is C. Solar cells convert solar energy directly into electricity without moving parts like turbines. Thermal, hydro, and nuclear power plants all require turbines to convert kinetic/thermal energy into mechanical energy for power generation.
Q4mcq1 mark
Imagine, you are holding a straight current carrying conductor as per the right hand thumb rule. If the thumb is upward, then the direction of the field lines of the magnetic field is
a.
downward
b.
upward
c.
anti-clockwise
Correct Answer
d.
clockwise
Step-by-Step AI Explanation
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The correct choice is C. According to the right-hand thumb rule, if the thumb points in the direction of the current (upward), the fingers curl in the direction of the magnetic field lines, which, viewed from above, is anti-clockwise.
Q5short answer1 mark
Draw the symbol diagram of rheostat used in electric circuit.
Step-by-Step AI Explanation
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A rheostat is represented by a resistor symbol with an arrow pointing across it or a slider moving along the resistor:
[Resistor Symbol] with a diagonal arrow pointing at it, or a zigzag line with an arrow touching the top.
Q6short answer1 mark
Observe the figure and mention the direction of the force acting on the current carrying conductor AB. Name the rule that helped you to find the direction of the force.
Step-by-Step AI Explanation
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The direction of the force is determined by Fleming's Left-Hand Rule. According to this rule, if the first finger points in the direction of the magnetic field and the second finger in the direction of the current, the thumb indicates the direction of the force acting on the conductor. (Note: Without the specific visual provided, the answer is based on the application of Fleming's Left-Hand Rule).
Q7short answer2 marks
Name any two fossil fuels and mention any two disadvantages of using fossil fuels.
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Two fossil fuels are: 1) Coal, 2) Petroleum. Two disadvantages of using fossil fuels are: 1) Burning them releases harmful greenhouse gases like $CO_2$, contributing to global warming. 2) They are non-renewable resources that will eventually be exhausted.
Q8short answer2 marks
$1000\text{ J}$ of heat is produced each $2\text{ seconds}$ in a $5\ \Omega$ resistor. Find the potential difference across the resistor.
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Q8short answer2 marks
OR: A wire of given material having length '$l$' and area of cross-section '$A$' has a resistance of '$4\ \Omega$'. Find the resistance of another wire of the same material having length '$l/2$' and area of cross-section '$2A$'.
Step-by-Step AI Explanation
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The resistance $R$ of a wire is given by the formula $R = \rho \frac{l}{A}$, where $\rho$ is the resistivity of the material. Given $R_1 = 4\ \Omega$ for length $l$ and area $A$. For the second wire, $l' = l/2$ and $A' = 2A$. The new resistance $R_2$ is: $R_2 = \rho \frac{l'}{A'} = \rho \frac{l/2}{2A} = \frac{1}{4} \rho \frac{l}{A} = \frac{1}{4} R_1$. Substituting $R_1 = 4\ \Omega$, we get $R_2 = \frac{1}{4} \times 4 = 1\ \Omega$.
Q9short answer3 marks
What is meant by the 'aperture' of a spherical mirror ? Mention the four uses of a concave mirror.
Step-by-Step AI Explanation
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Aperture: The diameter of the reflecting surface of a spherical mirror is called its aperture. Uses of a concave mirror: 1. Used in torches, search-lights, and headlights of vehicles to get parallel beams of light. 2. Used as shaving mirrors to see a larger image of the face. 3. Used by dentists to see enlarged images of patients' teeth. 4. Used in solar furnaces to concentrate sunlight to produce heat.
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OR: a) What is meant by the power of a lens ? Write the formula used to find the power of a lens. What is the SI unit of power of a lens? b) If the focal lengths of two lenses 'A' and 'B' are $+ 0.50\text{ m}$ and $- 0.40\text{ m}$ respectively. Mention the types of these lenses in the same order.
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Draw the ray diagram for the image formation by a convex lens, when the object is placed at $2F_1$. With the help of the ray diagram mention the position and the nature of the image formed. [$F_1$: Principal focus of the lens]
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a) A bread-toaster rated $350\text{ W}$ is used for $15\text{ hours}$ a day. An electric iron box rated $250\text{ W}$ is used for $5\text{ hours}$ a day. Calculate the cost of using these appliances for $30\text{ days}$, if the cost of $1\text{ kWh}$ is Rs. $4$. b) In which method the resistors $R_1$ and $R_2$ could be connected so that the equivalent resistance of that electric circuit becomes low? What is the change in the value of current in the circuit by this type of connection?
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a) How does the lens of human eye accommodate to see the nearby objects and the distant objects ? Explain.
b) Explain the formation of rainbow in the nature.
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In a homologous series, the first member of hydrocarbon group has the molecular formula $CH_4$. Then find out the molecular formula of the fourth member and write two types of structural formula of it.
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Add same amount of barium chloride solution to a test tube containing 5 ml of sodium sulphate solution. Then
i) Which insoluble white precipitate is formed ?
ii) Name the ions responsible for the formation of white precipitate.
iii) Mention the type of chemical reaction that took place here.
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Draw the diagram of arrangement of the apparatus used to show the action of steam on metal. Label the following parts :
i) Metal sample
ii) Delivery tube.
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The elements are arranged in the increasing order of their atomic masses in the below given table. Observe it and answer the following questions :
Sa Re Ga Ma Pa Dha Ni
H Li Be B C N O F Na
i) Name the elements that belong to the same group.
ii) State the law that helps to group these elements.
iii) Write two limitations of the same law.
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a) Identify unsaturated hydrocarbons in the following carbon compounds and write their structural formula. $C_6H_6, C_5H_{12}, C_2H_5OH, C_2H_2$.
b) Write the difference between esterification and saponification.
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a) Explain the manufacturing of bleaching powder. Write any two uses of it.
b) A strong solution of sodium hydroxide is added to the strong solution of hydrochloric acid. What is the nature of the salt solution formed here ? Write a balanced chemical equation for this reaction.
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Student ‘A’ tells to Student ‘B’ that the wing of bird and arm of human are analogous organs. Student ‘B’ replies both of them are homologous organs. Whose answer is correct? Justify your answer with suitable reasons.
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Round, green colour seeds producing pea plant ($RR yy$) is crossed with wrinkled, yellow colour seeds producing pea plant ($rr YY$). Show the result of $F_2$ generation with the help of a checker board and mention the ratio of varieties of plants.
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A strong solution of sodium hydroxide is added to the strong solution of hydrochloric acid. What is the nature of the salt solution formed here? Write a balanced chemical equation for this reaction.
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How are the traits of organisms classified as ‘dominant’ and ‘recessive’ traits? The experiences of an individual acquired during its life-time cannot be passed on to its progeny. Why?
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