CBSE JEE main Exam 7April 2013 : Question paper download : Answer key | Physics questions uploaded by Jobslip.in

Q : A sono meter wire at length 1.5 is made of steel. The tension in it produces an elastic strain of 1%. What is the fundamental frequency of steel it density and elasticity of steel are 7.7 x 1000 kg/m3 and 22 x 10 (Raised power 11) N/m2 respectively?

1) 188.5 Hz

(2) 178.2 HZ

(3) 200.5 HZ

(4) 770 HZ

Answer : 2

Q : The amplitude of a damped oscillator decreases to 0.9 times its original magnitude in 5s. In another l0 s it s ill decrease to ALPHA times its original magnitude. where ALPHA equals

(1) 0.7

(2) 0.81

(3) 0.729

(4) 0.6

Answer: 3

Q Two capacitors C1 and C2 , are charged to 120 V and 200 V respectively. It is found

that by connecting them together the potential on each one can be made zero.

Then:

(1) 5C1=3C2

(2) 3C1=5C2

(3) 3C1+5C2=0

(4) 9C1=4C2

Answer: 2

Q A circular loop of radius 0.3cm lies parallel to a much bigger circular loop of radius 20 cm. The centre of the small loop is or the axis of the bigger loop. The distance between the circentrcs is l5cm. If a current of 2.0 A flows through the smaller loop then the flux Linked with bigger loop is:

(1) 9.1X10 to raised power -11 weber

(2) 6x10 to raised power -11 weber

(3) 3.3x10 raised power -11 weber

(4) 6.6x10 to raised power -9 weber

Answer 1

Q : Diameter of a piano - convex lens is 6 cm and thickness at the centre is 3 mm. If speed of light in material of lens is 2x10 to raised power 8 m/s, the focal length of the lens is:

(1) 15 cm

(2) 20 cm

(3) 30cm

(4) 10 cm

Answer: Answer 3

Q : What is the minimum energy required to launch a satellite of mass m from the surface of a planet of mass M and radius R in a circular orbit at an altitude of 2R?

1 : 5 GmM / 6R

2 : 2GmmM/3R

3 : GmM/ 2R

4 : GmM / 3R

Answer: 1

Q A diode detector is used to detect an amplitude modulated wave of 60% modulation by using a condenser of capacity 250 pico farad in parallel with a load resistance 100 kilo ohm. Find the maximum modulated frequency which could be detected by it.

(1) 10.62 MHz

(2) 10.62 kHz

(3) 5.31 MHz

(4) 5.31 kHz

Answer: 2

Q : A beam of un polarised light of intensity I0 is passed through a Polaroid A and then through another Polaroid B which is oriented so that its principal plane makes an angle of 45 degree relative to that of A. The intensity of the emergent light Is:

(1) I0

(2) I0/2

(3) I0/4

(4) I0/8

Answer: 3

**SET P**Q : A sono meter wire at length 1.5 is made of steel. The tension in it produces an elastic strain of 1%. What is the fundamental frequency of steel it density and elasticity of steel are 7.7 x 1000 kg/m3 and 22 x 10 (Raised power 11) N/m2 respectively?

1) 188.5 Hz

(2) 178.2 HZ

(3) 200.5 HZ

(4) 770 HZ

Answer : 2

Q : The amplitude of a damped oscillator decreases to 0.9 times its original magnitude in 5s. In another l0 s it s ill decrease to ALPHA times its original magnitude. where ALPHA equals

(1) 0.7

(2) 0.81

(3) 0.729

(4) 0.6

Answer: 3

Q Two capacitors C1 and C2 , are charged to 120 V and 200 V respectively. It is found

that by connecting them together the potential on each one can be made zero.

Then:

(1) 5C1=3C2

(2) 3C1=5C2

(3) 3C1+5C2=0

(4) 9C1=4C2

Answer: 2

Q A circular loop of radius 0.3cm lies parallel to a much bigger circular loop of radius 20 cm. The centre of the small loop is or the axis of the bigger loop. The distance between the circentrcs is l5cm. If a current of 2.0 A flows through the smaller loop then the flux Linked with bigger loop is:

(1) 9.1X10 to raised power -11 weber

(2) 6x10 to raised power -11 weber

(3) 3.3x10 raised power -11 weber

(4) 6.6x10 to raised power -9 weber

Answer 1

Q : Diameter of a piano - convex lens is 6 cm and thickness at the centre is 3 mm. If speed of light in material of lens is 2x10 to raised power 8 m/s, the focal length of the lens is:

(1) 15 cm

(2) 20 cm

(3) 30cm

(4) 10 cm

Answer: Answer 3

Q : What is the minimum energy required to launch a satellite of mass m from the surface of a planet of mass M and radius R in a circular orbit at an altitude of 2R?

1 : 5 GmM / 6R

2 : 2GmmM/3R

3 : GmM/ 2R

4 : GmM / 3R

Answer: 1

Q A diode detector is used to detect an amplitude modulated wave of 60% modulation by using a condenser of capacity 250 pico farad in parallel with a load resistance 100 kilo ohm. Find the maximum modulated frequency which could be detected by it.

(1) 10.62 MHz

(2) 10.62 kHz

(3) 5.31 MHz

(4) 5.31 kHz

Answer: 2

Q : A beam of un polarised light of intensity I0 is passed through a Polaroid A and then through another Polaroid B which is oriented so that its principal plane makes an angle of 45 degree relative to that of A. The intensity of the emergent light Is:

(1) I0

(2) I0/2

(3) I0/4

(4) I0/8

Answer: 3

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