Curie temperature is the temperature above which
|
(a) A paramagnetic material becomes ferromagnetic |
|
(b) A ferromagnetic material becomes paramagnetic |
| (c) A paramagnetic material becomes diamagnetic |
|
(d) A ferromagnetic material becomes diamagnetic |
(b) A ferromagnetic material becomes paramagnetic
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A plane wavefront (λ = 6 
falls on a slit 0.4 mm wide. A convex lens of focal length 0.8 m placed behind the slit focusses the light on a screen. What is the linear diameter of second maximum
|
(a) 6mm |
(b) 12 mm |
(c) 3 mm |
(d) 9 mm |
A double convex lens (
having focal length equal to the focal length of a concave mirror. The radius of curvature of the concave mirror is
|
(a) 10 cm |
(b) 20 cm |
(c) 40 cm |
(d) 15 cm |
In radio theraphy, X-rays are used to
| (a) Detect bone fractures |
(b) Treat cancer by controlled exposure |
| (c) Detect heart diseases | (d) Detect fault in radio receiving circuits |
A small lamp is hung at a height of 8 feet above the centre of a round table of diameter 16 feet. The ratio of intensities of illumination at the centre and at points on the circumference of the table will be
|
(a) 1 : 1 |
(b) 2 : 1 |
(c) 2 |
(d) 3 : 2 |
The range of wavelength of the visible light is
|
(a) 10 Å to 100 Å |
(b) 4,000 Å to 8,000 Å |
(c) 8,000 Å to 10,000 Å |
(d) 10,000 Å to 15,000 Å |
