A blackbody at $1227^{\circ} \mathrm{C}$ emits radiation with maximum intensity at a wavelength of $5600 $$\mathop {\rm{A}}\limits^{\rm{o}} $. If the temperature of the body is increased by $1000^{\circ} \mathrm{C}$, the maximum intensity will be at wavelength
A resistor of $400 \Omega$, an inductance of 0.4 H are in series with an a.c. source of e.m.f. $\mathrm{E}=200 \sqrt{2} \sin (1000 \mathrm{t})$. The power factor of the circuit is
A plane wavefront of width ' $x$ ' is incident on an air-water interface and the corresponding refracted wavefront has a width ' y ' as shown in figure. The refractive index of air with respect to water in terms of distances ' $w$ ' and ' $z$ ' is $(\mathrm{AD}=\mathrm{w}, \mathrm{CB}=\mathrm{z})$

The intermediate image formed by an objective lens of a compound microscope is