JEE Mains · Physics · STD 12 - 9. Ray optics and optical instruments
A convex lens of focal length 30 cm is placed in contact with a concave lens of focal length 20 cm. An object is placed at 20 cm to the left of this lens system. The distance of the image from the lens in cm is ________
- A 30
- B 45
- C \(\frac{60}{7}\)
- D 15
Answer & Solution
Correct Answer
(D) 15
Step-by-step Solution
Detailed explanation
Equivalent focal length \(\begin{aligned} & \frac{1}{f}=\frac{1}{f_1}+\frac{1}{f_2} \\ & =\frac{1}{30}+\frac{1}{-20}=\frac{2-3}{60}=-\frac{1}{60} \\ & f=-60 \mathrm{~cm} \end{aligned}\) Lens formula…
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Physics
- The energy associated with electric field is \((U_E)\) and with magnetic field is \((U_B)\) for an electromagnetic wave in free space. ThenJEE Mains 2019 Medium
- Refer to the figure given below. The values of \(I_1\), \(I_2\) and \(I_3\) are __________.
JEE Mains 2026 Hard - In the electric network shown, when no current flows through the \(4\, \Omega \) resistor in the arm \(EB\), the potential difference between the points \(A\) and \(D\) will be ............... \(V\)
JEE Mains 2015 Hard - For a rolling spherical shell, the ratio of rotational kinetic energy and total kinetic energy is \(\frac{x}{5}\). The value of \(x\) is ................JEE Mains 2023 Medium
- A spherically symmetric charge distribution is characterised by a charge density having the following variations \(\rho (r)\, = \,{\rho _0}\left( {1 - \frac{r}{R}} \right)\) for \(r < R\) \(\rho (r)\,=\,0\) for \(r\, \ge \,R\) Where \(r\) is the distance from the centre of the charge distribution \(\rho _0\) is a constant. The electric field at an internal point \((r < R)\) isJEE Mains 2014 Hard
- At some instant, a radioactive sample \(S_1\) having an activity \(5\,\mu Ci\) has twice the number of nuclei as another sample \(S_2\) which has an activity of \(10\,\mu Ci.\) The halflives of \(S_1\) and \(S_2\) areJEE Mains 2018 Hard
More PYQs from JEE Mains
- If two vertices of an equilateral triangle are \(A (- a, 0)\) and \(B ( a, 0),\,a > 0,\) and the third vertex \(C\) lies above \(x-\) axis then the equation of the circumcircle of \(\Delta ABC\) isJEE Mains 2013 Hard
- An oscillating \(LC\) circuit consists of a \(75\,mH\) inductor and a \(1.2\,\mu F\) capacitor. If the maximum charge to the capacitor is \(2.7\,\mu C\). The maximum current in the circuit will be \(...........\,mA\).JEE Mains 2023 Medium
- Consider a triangular plot \(ABC\) with sides \(AB = 7\, m\), \(BC = 5\, m\) and \(CA = 6\, m\). A vertical lamp-post at the mid point \(D\) of \(AC\) subtends an angle \(30^o\) at \(B\). The height (in \(m\)) of the lamp-post isJEE Mains 2019 Hard
- For the network shown below, the value \(V _{ B }- V _{ A }\) is_______ \(V\)
JEE Mains 2022 Medium - The magnitude of magnetic induction at mid-point \(O\) due to current arrangement as shown in Fig will be
JEE Mains 2023 Medium - An electron of mass \(m _{ e }\) and a proton of mass \(m _{ p }=1836 m _{ e }\) are moving with the same speed. The ratio of their de Broglie wavelength \(\frac{\lambda_{\text {electron }}}{\lambda_{\text {proton }}}\) will be ....... .JEE Mains 2021 Medium