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Which of the following statements is/are true in case of an incandescent filament bulb?
- (a) Filament can be made of tungsten or nichrome.
- (b) The glass envelope covering the filament is filled with inactive gases such as nitrogen or argon.
- (c) Since the filament used is thin, its resistivity is very low.
- (d) The resistivity of the filament is low to allow more current.
- (e) The filament material used should have high melting point.
Induced EMF in a coil during the phenomenon of electromagnetic induction is directly proportional to?
An object is placed at a distance of 10 cm in front of a concave mirror. Its image is formed at a distance at 15 cm on the same side. The focal length of the mirror is?
In which of the following cases does a concave mirror form a real image?
- (i) Object placed between focus and pole
- (ii) Object placed at infinity
- (iii) Object placed at focus
The resistance of a wire of length Land area of cross-section A is 1.0 Ω . The resistance of a wire of the same material, but of length 41 and area of cross-section 5A will be?
The potential difference across a copper wire is 5.0 V when a current of 0.5 A flows through it. The resistance of the wire is?
Two resistors. A (20Ω) and B (30Ω), are connected in parallel. The combination is connected to a 3 V battery. The current through the battery is?
Consider the following statements: Which of the above statements help(s) us to understand the blue colour of a clear sky?
- (a) The red light has a wavelength about 1.8 times greater than the blue light.
- b) When sunlight passes through the atmosphere, the fine particles scatter blue light more strongly than red.
A current-carrying straight conductor is placed in a magnetic field. The conductor experiences the maximum force when the angle between the direction of the current in it and the direction of the magnetic field is?
ചേരുംപടി ചേർക്കുക.
| താപനില അളക്കുന്ന ഉപകരണം | ക്രയോമീറ്റർ |
| ഉയർന്ന താപനില അളക്കുന്ന ഉപകരണം | ഹീലിയോ പൈറോമീറ്റർ |
| സൂര്യനിലെ താപനില അളക്കുന്ന ഉപകരണം | പൈറോമീറ്റർ |
| താഴ്ന്ന താപനില അളക്കുന്ന ഉപകരണം | തെർമോമീറ്റർ |
A concave mirror converges light rays from the sun at 10 cm from the mirror. If an object is placed 20 cm from the mirror, the image is formed?
Two resistors. A of 10Ω and B of 30Ω, are connected in series to a battery of 6 V. The total heat dissipated in the resistors in 1 second is?
A lens having power 8 D is kept in contact with another lens having power -4 D. The lens combination will act as a?
Consider the following statements about magnetic field due to a current-carrying straight conductor: Which of the above statements is/are correct?
- (a) The direction of the south pole of a compass needle at a point gives the direction of the magnetic field at that point.
- (b) The direction of the magnetic field lines gets reversed if the direction of the current in the conductor is reversed.
The potential difference across a copper wire is 2.0 V when a current of 0.4 A flows through it. The resistance of the wire is?
An object is placed in front of a concave mirror of focal length 12 cm, at a distance of 8 cm. Its image is formed at a distance of?
Two resistors, A of 6 Ω and B of 12 Ω, are connected in parallel to a battery of 3 V. The total energy supplied by the battery to the circuit in 1 second is ?
An object is placed at a distance of 30 cm in front of a concave mirror of focal length 15 cm. The image formed is?
Two metallic wires A and B are made of the same material. Wire A has length 1 and radius r while wire B has length 21 and radius 21. The ratio of the resistance of wire A to that of wire B is?
Two resistors A and B have resistances 5 chm and 10 ohm, respectively. If they are connected in series to a voltage source of 5 V. The ratio of power developed in resistor A to that of power developed in resistor B will be?
An object is placed on the principal axis of a convex lens of focal length 12 cm, at a distance magnification produced by the lens is ______and the image is_______?
A ray of light bends towards the normal while travelling from medium A to medam B. Which of the following statements is are correct?
- (A) Medium A is optically denser than medium B.
- (B) Speed of light is more in medium A than medium B.
- (C) Refractive index of medium B is more than refractive index of medium A.
Which of the following method(s) can be used to change the direction of force on a current carrying conductor?
- (i) Changing the magnitude of current
- (ii) Changing the strength of magnetic field
- (iii) Changing the direction of current
An object. 3.0 cm in height, is placed at a distance of 20.0 cm in front of a convex mirror of focal length 6.0 cm. on its principal axis. Its image has a height of _______and is_____?
A light ray is travelling from air medium to water medium (refractive index = 1.3) such that angle of incidence is x degree and angle of refraction is y degree. The value of ratio (sin y)/ (sin x) is?