When a metallic surface is illuminated with radiation of wavelength $\lambda$,the stopping potential is $V$. If the same surface is illuminated with radiation of wavelength $2\lambda$,the stopping potential is $\frac{V}{4}$. The threshold wavelength for the metallic surface is:

Two resistances $X$ and $Y$ are connected in the two gaps of a meter bridge,and the null point is obtained at $20 \text{ cm}$ from the zero end. When a resistance of $20 \text{ } \Omega$ is connected in series with the smaller of the two resistances $X$ and $Y$,the null point shifts to $40 \text{ cm}$ from the left end. The value of the smaller resistance in ohms is:

The image of the line $x+y-2=0$ in the $y$-axis is

Which one of the following generally acts as an antagonist to gibberellins?

For all values of $\theta$,the values of $3-\cos \theta+\cos \left(\theta+\frac{\pi}{3}\right)$ lie in the interval :

The joint equation of the lines passing through the origin and trisecting the first quadrant is . . . . . .