## Why is the objective lens of a refracting telescope should have a longer focal length?

The longer the focal length, the larger the image. The brightness of an image from a telescope depends partly on how much light is collected by the telescope. The light-gathering power of a telescope is directly proportional to the area of the objective lens.

### What’s the objective lens of a refracting telescope?

A simple refracting telescope may be constructed from a pair of convex lenses, where the larger of the two lenses is the objective. This lens produces a real imagereal imageA real image occurs where rays converge, whereas a virtual image occurs where rays only appear to diverge. Real images can be produced by concave mirrors and converging lenses, only if the object is placed further away from the mirror/lens than the focal point, and this real image is inverted.https://en.wikipedia.org › wiki › Real_imageReal image – Wikipedia at the focal plane that is viewed with an eyepiece.

#### What is the focal length of a refracting telescope?

The magnification of a refracting telescope is equal to the focal length of the objective divided by the focal length of the eyepiece. e.g. a refracting telescope has an objective of focal length 70cm and eyepiece 5cm. Its magnification will be 70 / 5 = 14. Star gazers usually have a selection of eyepieces at hand.

**What is the focal length of the objective lens of the telescope?**

focal length of objective lens and eye piece of an astronomical telescope are 200 cm and 10 cm respectively.

**Why the objective lens of a refracting telescope is much larger than the objective lens of a compound microscope?**

For a spherical mirror, the focal length is half the radius of curvature, so making a large objective mirror not only helps the telescope collect more light, but also increases the magnification of the image.

## Why is the focal length of the objective lens in a microscope short?

EXPLANATION: Since the magnification of a compound microscope is inversely proportional to the focal length of objective lens. So to get the maximum magnification the focal length of the objective lens must be less than the focal length of eyepiece.

### Which type of lens is used in refracting telescope?

convex lens

It uses a convex lens as the eyepiece instead of Galileo’s concave one. The advantage of this arrangement is that the rays of light emerging from the eyepiece are converging. This allows for a much wider field of view and greater eye relief, but the image for the viewer is inverted.

#### What do you think the primary or objective lens of a refracting?

A refractor is made up of a long tube containing lenses. The objective lens is the front lens. In other words, it’s the lens at the end where the light comes in.

**What is focal length of a lens?**

The focal length of a lens is determined when the lens is focused at infinity. Lens focal length tells us the angle of view—how much of the scene will be captured—and the magnification—how large individual elements will be. The longer the focal length, the narrower the angle of view and the higher the magnification.

**What is focal length of objective for large magnification?**

So the magnification is directly proportional to the focal length of the objective lens and inversely proportional to the focal length of the eye piece. Hence it ensures large magnification of the distant object. Was this answer helpful?

## In which of the following instruments is the focal length of the objective lens larger than that of the eyepiece?

The focal length of the objective in a telescope is larger than that of eyepiece.

### Which lens has more focal length in microscope?

Solution : Thin lens will have greater focal length.

#### Why both objective and eyepiece of a compound microscope have short focal length?

Keeping both objective focal length and eyepiece focal length small makes the magnifying power greater and more effective. Short focal length leads to larger magnification of both the lenses. This increases the magnifying power/ angular magnification of the microscope.

**Which type of lens is used in refracting telescope concave or convex?**

Refracting telescopes work by using two lenses to focus the light and make it look like the object is closer to you. Both lenses are in a shape that’s called convex. Was this answer helpful?

**What lens has a single focal length?**

A single focal length lens is often called a prime lens. There are only really two key types of lenses from a focal-range standpoint: primes and zooms. In most cases, a prime lens is optically superior to a zoom lens of similar focal lengths, and tend to have larger maximum apertures.

## Which type of lens has long focal length?

telephoto lenses

Lenses with long focal lengths are called telephoto lenses, and have a smaller field of view. 2. Depth of field. Lenses with long focal lengths tend to have a shallow depth of field, which means they can focus in on small objects (even faraway ones) at specific distances.

### What is the focal length of the objective?

The focal length of a microscope objective is typically between 2 mm and 40 mm. However, that parameter is often considered as less important, since magnification and numerical aperture are sufficient for quantifying the essential performance in a microscope.

#### Why should the objective of a telescope have large focal length and large aperture justify your?

Solution : Objective of a telescope is a convex lens of large focal length, because it faces distant object and bright image of distant objects. <br> The aperture of the objective is taken large so that it can gather sufficient amount of light from the distant objects.

**Which objective lens has the shortest focal length?**

Focal length is the shortest with the oil immersion objective lens.

**Why does objective lens have small focal length?**

The objective lens is the convex lens that is closest to the object, and the eye piece is the convex lens that is closest to the eye. Because a limited focal length necessitates a tiny aperture, the objective lens has a small focal length and aperture.

## Why is eyepiece of telescope of short focal length while objective is of large focal length explain?

When the focal length of eyepiece decreases the magnification increases. We get a bigger and clearer image of the object viewed.

### Why is a convex lens used in refracting telescope?

A refracting telescope works just like a magnifying glass. It uses a convex glass lens (to bend light and bring it into focus. This lens is thicker in the center than it is toward its edges, which bends the light more at the edge of the lens than light coming through the center.

#### What lens has multiple focal lengths?

zoom

There are two types of lenses-prime and zoom. Prime lenses have a fixed focal length and zoom lenses have variable focal lengths.

**What is focal length of convex lens?**

Focal length of a convex lens is denoted by f which is the difference between optical centre of the lens and the principal Focus. The image would be real, inverted and smaller in size if it is formed at the focus of the lens. The refracted Ray converges on the other side of the convex lens.

**What is the focal length of the lens?**