The continuous X-rays spectrum produced by an X-ray machine at constant voltage has
| (a) A maximum wavelength | (b) A minimum wavelength |
|
(c) A single wavelength |
(d) A minimum frequency |
The continuous X-rays spectrum produced by an X-ray machine at constant voltage has
| (a) A maximum wavelength | (b) A minimum wavelength |
|
(c) A single wavelength |
(d) A minimum frequency |
(b) A minimum wavelength
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Figure shows three points A, B and C in a region of uniform electric field . The line AB is perpendicular and BC is parallel to the field lines. Then which of the following holds good. Where
and
represent the electric potential at points A, B and C respectively
|
(a) |
(b) |
(c) |
(d) |
$8\ \pi\text{r}^2\text{S}$
$12\ \pi\text{r}^2\text{S}$
$16\ \pi\text{r}^2\text{S}$
$24\ \pi\text{r}^2\text{S}\cdot$
A star which appears blue will be
|
(a) As hot as the sun |
(b) Cooler than the sun |
|
(c) Very cold indeed |
(d) Much hotter than the sun |
Assertion : The induced e.m.f. and current will be same in two identical loops of copper and aluminium, when rotated with same speed in the same magnetic field.
Reason : Induced e.m.f. is proportional to rate of change of magnetic field while induced current depends on resistance of wire.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If assertion is false but reason is true. |
The angle of dip is the angle
|
(a) Between the vertical component of earth's magnetic field and magnetic meridian |
|
(b) Between the vertical component of earth's magnetic field and geographical meridian |
|
(c) Between the earth's magnetic field direction and horizontal direction |
|
(d) Between the magnetic meridian and the geographical meridian |