Two identical thin plano-convex glasses lenses (refractive index 1.5) each having radius of curvature of 20 cms are placed with their convex surfaces in contact at the centre. The intervening space is filled with oil of refractive index 1.7. The focal length of the combination is

• -20 cm

• -25 cm

• -50 cm

• -50 cm

Which of the following figures represent the variation of particle momentum and the associated de-Broglie wavelength?

43.

If in a p-n junction, a square input signal of 10 V is applied as shown,


then the output across R_L will be

• 

• 

• 

• 

Which logic gate is represented by this following combination of logic gates?

• OR

• NAND

• AND

• AND