(1). When p-n junction diode is forward biased then

• (a). both the depletion region and barrier height are reduced
• (b). the depletion region is widened and barrier height is reduced
• (c). the depletion region is reduced and barrier height is increased
• (d). both the depletion region and barrier height are increased
• (e). None of these

(2). The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than 2480nm is incident on it. the band gap in (eV) for the semiconductor is

• (a). 2.5eV
• (b). 1.1eV
• (c). 0.7eV
• (d). 0.5eV
• (e). None of these

(3). Carbon silicon and germanium have four valence electrons each. At room temperature which one of the following statements is most appropriate?

• (a). the number of free electrons for conduction is significant only in si and ge but small in C
• (b). the number of free conduction electrons is significant in C but small in si and ge
• (c). the number of free conduction electrons is negligibly small in all the three
• (d). the number of free electrons for conduction is significant in all the three
• (e). None of these

(4). A working transistor with its three legs marked P,Q and R is tested using a multimeter. No conduction is found between P and Q. by connecting the common(negative) terminal of the multimeter to R and the other (positive) terminal to P or Q, some resistance is seen on the multimeter. which of the following is true for the transistor?

• (a). it is an npn transistor with R as base
• (b). it is a pnp transistor with R as collector
• (c). it is a pnp transistor with R as emitter
• (d). it is an npn transistor with R as collector
• (e). None of these

• (a). 1
• (b). 2
• (c). 3
• (d). 4
• (e). None of these

• (a). 49
• (b). 50
• (c). 54
• (d). 48
• (e). None of these

• (a). 1
• (b). 2
• (c). 3
• (d). 4
• (e). None of these

• (a). NOR gate
• (b). AND gate
• (c). NAND gate
• (d). OR gate
• (e). None of these

• (a). 1
• (b). 2
• (c). 3
• (d). 4
• (e). None of these

• (a). 1
• (b). 2
• (c). 3
• (d). 4
• (e). None of these