At a certain place,the horizontal component of the Earth's magnetic field is $B_0$ and the angle of dip is $45^o$. The total intensity of the field at that place will be:

If the length of the filament of a heater is reduced by $10\%$,the power of the heater will

Which of the following is an accessory whorl of a flower?

$1+\frac{2}{4}+\frac{2 \cdot 5}{4 \cdot 8}+\frac{2 \cdot 5 \cdot 8}{4 \cdot 8 \cdot 12}+\frac{2 \cdot 5 \cdot 8 \cdot 11}{4 \cdot 8 \cdot 12 \cdot 16}+\ldots \ldots$ is equal to :

In some respects,lithium differs from other alkali metals. Which of the following is the main reason for this?

Two coherent narrow slits emitting light of wavelength $\lambda$ in the same phase are placed parallel to each other at a small separation of $3\lambda$. The light is collected on a screen $S$ which is placed at a distance $D$ from the slits. Find the smallest distance $x$ from the central point $O$ such that point $P$ is a maxima.