An electric generator is a device that converts mechanical energy into electrical energy. A galvanometer detects current, an ammeter measures current, and an electric motor converts electrical energy into mechanical energy.
Q2mcq1 mark
The correct formula that shows the relationship between potential difference, electric current and resistance in an electric circuit is
a.
$I = \frac{V}{R}$
Correct Answer
b.
$I = VR$
c.
$V = \frac{R}{I}$
d.
$R = \frac{I}{V}$
Step-by-Step AI Explanation
Verified Method
According to Ohm's Law, $V = IR$, where $V$ is potential difference, $I$ is current, and $R$ is resistance. Rearranging this formula for $I$ gives $I = \frac{V}{R}$. Thus, option A is the correct relationship.
Q3mcq1 mark
In Fleming’s right hand rule, the middle finger indicates the direction of
a.
induced electric current
Correct Answer
b.
magnetic field
c.
motion of the conductor
d.
mechanical force.
Step-by-Step AI Explanation
Verified Method
According to Fleming's right-hand rule, the thumb indicates the direction of motion of the conductor, the forefinger indicates the direction of the magnetic field, and the middle finger indicates the direction of the induced electric current.
Q4mcq1 mark
To get diminished and real image of an object from a convex lens, the object should be placed
a.
at principal focus $F_1$
b.
between principal focus $F_1$ and $2F_1$
c.
beyond $2F_1$
Correct Answer
d.
between principal focus $F_1$ and optical centre O.
Step-by-Step AI Explanation
Verified Method
For a convex lens, when an object is placed beyond $2F_1$, the image formed is real, inverted, and diminished, and it is formed between $F_2$ and $2F_2$.
Q5short answer1 mark
Magnetic field lines do not intersect each other. Why ?
Step-by-Step AI Explanation
Verified Method
Magnetic field lines do not intersect each other because if they did, there would be two directions of the magnetic field at the point of intersection, which is physically impossible.
Q6short answer1 mark
Mention the SI unit of power of lens.
Step-by-Step AI Explanation
Verified Method
The SI unit of the power of a lens is Dioptre (D).
Q7short answer2 marks
Draw the schematic diagram of an electric circuit comprising of electric cell, electric bulb, ammeter and plug key.
Step-by-Step AI Explanation
Verified Method
A schematic diagram consists of a battery (or cell) represented by parallel lines, an electric bulb represented by a loop or cross in a circle, an ammeter connected in series (labeled 'A'), and a plug key (switch). The components should be connected in a closed loop with the ammeter positive terminal connected to the positive terminal of the cell.
Q8short answer2 marks
An object is placed at 25 cm in front of a concave mirror of focal length 15 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image? OR A concave lens has focal length of 15 cm. At what distance should the object from the lens be placed so that it forms an image at 10 cm from the lens?
Step-by-Step AI Explanation
Verified Method
For the concave mirror: Given $u = -25$ cm, $f = -15$ cm. Using the mirror formula $\frac{1}{f} = \frac{1}{v} + \frac{1}{u}$, we have $\frac{1}{-15} = \frac{1}{v} + \frac{1}{-25}$. Rearranging gives $\frac{1}{v} = \frac{1}{25} - \frac{1}{15} = \frac{3-5}{75} = \frac{-2}{75}$. Thus, $v = -37.5$ cm. The screen should be placed at 37.5 cm in front of the mirror. OR For the concave lens: Given $f = -15$ cm, $v = -10$ cm. Using $\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$, we get $\frac{1}{-15} = \frac{1}{-10} - \frac{1}{u}$. Rearranging, $\frac{1}{u} = \frac{1}{15} - \frac{1}{10} = \frac{2-3}{30} = \frac{-1}{30}$. Thus, $u = -30$ cm. The object should be placed 30 cm from the lens.
Q9long answer3 marks
Which is the major component of biogas ? Write four characteristics of a good source of energy. OR Which element is used in making solar cell ? Write any four advantages of solar cells.
Step-by-Step AI Explanation
Verified Method
The major component of biogas is methane ($CH_4$).
Characteristics of a good source of energy:
1. It should have a high calorific value (produce a large amount of heat per unit mass).
2. It should be easily accessible and easy to transport.
3. It should be economical and affordable.
4. It should be easy to store and use.
OR
The element used in making solar cells is Silicon.
Advantages of solar cells:
1. They have no moving parts and require little maintenance.
2. They can be set up in remote areas where power transmission lines are difficult to install.
3. They are environmentally friendly as they do not produce any pollution.
4. They utilize a renewable source of energy (sunlight).
Q10long answer3 marks
Draw the ray diagram to show the image formation by a convex lens, when the object is kept at $2F_1$ of the lens. With the help of the ray diagram mention the position and nature of the image formed. [$F_1$ : Principal focus of the lens]
Step-by-Step AI Explanation
Verified Method
Ray Diagram description:
When an object is placed at $2F_1$ in front of a convex lens:
1. A ray passing parallel to the principal axis passes through the focus $F_2$ on the other side.
2. A ray passing through the optical centre $O$ goes straight without deviation.
3. The image is formed at $2F_2$ on the other side of the lens.
Nature of image:
- Position: At $2F_2$.
- Size: Same size as the object.
- Nature: Real and inverted.
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OR
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