266566
An object of size 3.0 cm is placed 14 cm in front of a concave lens of focal length 21 cm . Describe at the image produced by the long lens:
1 \(-5.4 \mathrm{~cm}, 3.8 \mathrm{~cm}\)
2 \(-6.4 \mathrm{~cm}, 2.8 \mathrm{~cm}\)
3 \(-7.4 \mathrm{~cm}, 3.8 \mathrm{~cm}\)
4 \(-8.4 \mathrm{~cm}, 1.8 \mathrm{~cm}\)
Explanation:
d \(0=3.0 \mathrm{~cm}, u=-14 \mathrm{~cm}, \mathrm{f}=-21 \mathrm{~cm}\) (concave เепs) As, \(\frac{1}{f}=\frac{1}{v}-\frac{1}{u}\) \(\frac{1}{-21}=\frac{1}{v}-\frac{1}{-14}=\frac{1}{v}+\frac{1}{14}\) or \(\frac{1}{v}=-\frac{1}{-21}-\frac{1}{14}=-\frac{5}{42}\) or \(v=-\frac{42}{5}=-84 \mathrm{~cm}\) Since \(v\) is negative, the image is virtual. Further, as \(\frac{\mathrm{I}}{\mathrm{O}}=\frac{\mathrm{v}}{\mathrm{u}} \Rightarrow \mathrm{I}=\frac{\mathrm{v}}{\mathrm{u}} \times \mathrm{O}\) or \(\mathrm{I}={ }_{-14}^{-8.4} \times 3.0 \mathrm{~cm}=1.8 \mathrm{~cm}\)
TEST SERIES (PHYSICS FST)
266567
An astronomical telescope having magnifying power of 5 consists of two thin lenses 24 cm apart. Find the focal length of the lenses:
1 \(5 \mathrm{~cm}, 10 \mathrm{~cm}\)
2 \(10 \mathrm{~cm}, 4 \mathrm{~cm}\)
3 \(15 \mathrm{~cm}, 5 \mathrm{~cm}\)
4 \(20 \mathrm{~cm}, 4 \mathrm{~cm}\)
Explanation:
d \(f_0+f_e=24 \mathrm{~cm}\) and \(M=\frac{f_0}{f_e}=5\) or \(f_0=5 f_e\) Fromeqn. (1) and (2), \[ \begin{aligned} & 5 f_e+f_e=24 \text { or } 6 f_e=24 \\ & f_e=\frac{24}{6}=4 \mathrm{~cm} \end{aligned} \] and \(f_0=5 f_e=5 \times 4=20 \mathrm{~cm}\).
TEST SERIES (PHYSICS FST)
266568
An c-particle of mass \(m_{. .}\)and a proton of mass \(m_p\) are accelerated through the same potential difference. The ratio of the de Broglie wavelength associated with an e-particle to that associated with proton is:
266569
In Young's double slits experiment carried out with light of wavelength 5000A, the distance between the slits is 0.2 mm and the screen is at 2 meter from the slits. Position of \(3^{\text {rd }}\) maximum from centre of screen is -
266566
An object of size 3.0 cm is placed 14 cm in front of a concave lens of focal length 21 cm . Describe at the image produced by the long lens:
1 \(-5.4 \mathrm{~cm}, 3.8 \mathrm{~cm}\)
2 \(-6.4 \mathrm{~cm}, 2.8 \mathrm{~cm}\)
3 \(-7.4 \mathrm{~cm}, 3.8 \mathrm{~cm}\)
4 \(-8.4 \mathrm{~cm}, 1.8 \mathrm{~cm}\)
Explanation:
d \(0=3.0 \mathrm{~cm}, u=-14 \mathrm{~cm}, \mathrm{f}=-21 \mathrm{~cm}\) (concave เепs) As, \(\frac{1}{f}=\frac{1}{v}-\frac{1}{u}\) \(\frac{1}{-21}=\frac{1}{v}-\frac{1}{-14}=\frac{1}{v}+\frac{1}{14}\) or \(\frac{1}{v}=-\frac{1}{-21}-\frac{1}{14}=-\frac{5}{42}\) or \(v=-\frac{42}{5}=-84 \mathrm{~cm}\) Since \(v\) is negative, the image is virtual. Further, as \(\frac{\mathrm{I}}{\mathrm{O}}=\frac{\mathrm{v}}{\mathrm{u}} \Rightarrow \mathrm{I}=\frac{\mathrm{v}}{\mathrm{u}} \times \mathrm{O}\) or \(\mathrm{I}={ }_{-14}^{-8.4} \times 3.0 \mathrm{~cm}=1.8 \mathrm{~cm}\)
TEST SERIES (PHYSICS FST)
266567
An astronomical telescope having magnifying power of 5 consists of two thin lenses 24 cm apart. Find the focal length of the lenses:
1 \(5 \mathrm{~cm}, 10 \mathrm{~cm}\)
2 \(10 \mathrm{~cm}, 4 \mathrm{~cm}\)
3 \(15 \mathrm{~cm}, 5 \mathrm{~cm}\)
4 \(20 \mathrm{~cm}, 4 \mathrm{~cm}\)
Explanation:
d \(f_0+f_e=24 \mathrm{~cm}\) and \(M=\frac{f_0}{f_e}=5\) or \(f_0=5 f_e\) Fromeqn. (1) and (2), \[ \begin{aligned} & 5 f_e+f_e=24 \text { or } 6 f_e=24 \\ & f_e=\frac{24}{6}=4 \mathrm{~cm} \end{aligned} \] and \(f_0=5 f_e=5 \times 4=20 \mathrm{~cm}\).
TEST SERIES (PHYSICS FST)
266568
An c-particle of mass \(m_{. .}\)and a proton of mass \(m_p\) are accelerated through the same potential difference. The ratio of the de Broglie wavelength associated with an e-particle to that associated with proton is:
266569
In Young's double slits experiment carried out with light of wavelength 5000A, the distance between the slits is 0.2 mm and the screen is at 2 meter from the slits. Position of \(3^{\text {rd }}\) maximum from centre of screen is -
266566
An object of size 3.0 cm is placed 14 cm in front of a concave lens of focal length 21 cm . Describe at the image produced by the long lens:
1 \(-5.4 \mathrm{~cm}, 3.8 \mathrm{~cm}\)
2 \(-6.4 \mathrm{~cm}, 2.8 \mathrm{~cm}\)
3 \(-7.4 \mathrm{~cm}, 3.8 \mathrm{~cm}\)
4 \(-8.4 \mathrm{~cm}, 1.8 \mathrm{~cm}\)
Explanation:
d \(0=3.0 \mathrm{~cm}, u=-14 \mathrm{~cm}, \mathrm{f}=-21 \mathrm{~cm}\) (concave เепs) As, \(\frac{1}{f}=\frac{1}{v}-\frac{1}{u}\) \(\frac{1}{-21}=\frac{1}{v}-\frac{1}{-14}=\frac{1}{v}+\frac{1}{14}\) or \(\frac{1}{v}=-\frac{1}{-21}-\frac{1}{14}=-\frac{5}{42}\) or \(v=-\frac{42}{5}=-84 \mathrm{~cm}\) Since \(v\) is negative, the image is virtual. Further, as \(\frac{\mathrm{I}}{\mathrm{O}}=\frac{\mathrm{v}}{\mathrm{u}} \Rightarrow \mathrm{I}=\frac{\mathrm{v}}{\mathrm{u}} \times \mathrm{O}\) or \(\mathrm{I}={ }_{-14}^{-8.4} \times 3.0 \mathrm{~cm}=1.8 \mathrm{~cm}\)
TEST SERIES (PHYSICS FST)
266567
An astronomical telescope having magnifying power of 5 consists of two thin lenses 24 cm apart. Find the focal length of the lenses:
1 \(5 \mathrm{~cm}, 10 \mathrm{~cm}\)
2 \(10 \mathrm{~cm}, 4 \mathrm{~cm}\)
3 \(15 \mathrm{~cm}, 5 \mathrm{~cm}\)
4 \(20 \mathrm{~cm}, 4 \mathrm{~cm}\)
Explanation:
d \(f_0+f_e=24 \mathrm{~cm}\) and \(M=\frac{f_0}{f_e}=5\) or \(f_0=5 f_e\) Fromeqn. (1) and (2), \[ \begin{aligned} & 5 f_e+f_e=24 \text { or } 6 f_e=24 \\ & f_e=\frac{24}{6}=4 \mathrm{~cm} \end{aligned} \] and \(f_0=5 f_e=5 \times 4=20 \mathrm{~cm}\).
TEST SERIES (PHYSICS FST)
266568
An c-particle of mass \(m_{. .}\)and a proton of mass \(m_p\) are accelerated through the same potential difference. The ratio of the de Broglie wavelength associated with an e-particle to that associated with proton is:
266569
In Young's double slits experiment carried out with light of wavelength 5000A, the distance between the slits is 0.2 mm and the screen is at 2 meter from the slits. Position of \(3^{\text {rd }}\) maximum from centre of screen is -
266566
An object of size 3.0 cm is placed 14 cm in front of a concave lens of focal length 21 cm . Describe at the image produced by the long lens:
1 \(-5.4 \mathrm{~cm}, 3.8 \mathrm{~cm}\)
2 \(-6.4 \mathrm{~cm}, 2.8 \mathrm{~cm}\)
3 \(-7.4 \mathrm{~cm}, 3.8 \mathrm{~cm}\)
4 \(-8.4 \mathrm{~cm}, 1.8 \mathrm{~cm}\)
Explanation:
d \(0=3.0 \mathrm{~cm}, u=-14 \mathrm{~cm}, \mathrm{f}=-21 \mathrm{~cm}\) (concave เепs) As, \(\frac{1}{f}=\frac{1}{v}-\frac{1}{u}\) \(\frac{1}{-21}=\frac{1}{v}-\frac{1}{-14}=\frac{1}{v}+\frac{1}{14}\) or \(\frac{1}{v}=-\frac{1}{-21}-\frac{1}{14}=-\frac{5}{42}\) or \(v=-\frac{42}{5}=-84 \mathrm{~cm}\) Since \(v\) is negative, the image is virtual. Further, as \(\frac{\mathrm{I}}{\mathrm{O}}=\frac{\mathrm{v}}{\mathrm{u}} \Rightarrow \mathrm{I}=\frac{\mathrm{v}}{\mathrm{u}} \times \mathrm{O}\) or \(\mathrm{I}={ }_{-14}^{-8.4} \times 3.0 \mathrm{~cm}=1.8 \mathrm{~cm}\)
TEST SERIES (PHYSICS FST)
266567
An astronomical telescope having magnifying power of 5 consists of two thin lenses 24 cm apart. Find the focal length of the lenses:
1 \(5 \mathrm{~cm}, 10 \mathrm{~cm}\)
2 \(10 \mathrm{~cm}, 4 \mathrm{~cm}\)
3 \(15 \mathrm{~cm}, 5 \mathrm{~cm}\)
4 \(20 \mathrm{~cm}, 4 \mathrm{~cm}\)
Explanation:
d \(f_0+f_e=24 \mathrm{~cm}\) and \(M=\frac{f_0}{f_e}=5\) or \(f_0=5 f_e\) Fromeqn. (1) and (2), \[ \begin{aligned} & 5 f_e+f_e=24 \text { or } 6 f_e=24 \\ & f_e=\frac{24}{6}=4 \mathrm{~cm} \end{aligned} \] and \(f_0=5 f_e=5 \times 4=20 \mathrm{~cm}\).
TEST SERIES (PHYSICS FST)
266568
An c-particle of mass \(m_{. .}\)and a proton of mass \(m_p\) are accelerated through the same potential difference. The ratio of the de Broglie wavelength associated with an e-particle to that associated with proton is:
266569
In Young's double slits experiment carried out with light of wavelength 5000A, the distance between the slits is 0.2 mm and the screen is at 2 meter from the slits. Position of \(3^{\text {rd }}\) maximum from centre of screen is -
