MCQ
Electrochromic Devices MCQ - Practice Questions with Answers
Solve 97 Electrochromic Devices questions for RAS/RPSC preparation.
Practice questions
Q1Consider the following statements about the smart oxide reported by DST: 1. Oxygen vacancies were described as creating extra space and active sites in the lattice. 2. Ion movement during charge storage triggered a shift in electronic structure and visible colour change. 3. The device was reported to power an LCD timer and light an LED. 4. The material lost function under mechanical bending according to the report. Which of the statements given above are correct?
Statements 1 and 2 are correct because the DST release links oxygen deficiency, ion movement, electronic-structure change and visible colour change. Statement 3 is correct because the device powered an LCD timer and lit an LED. Statement 4 is false because the report says functionality was retained under mechanical bending and environmental conditions.
Q2Consider the following statements about the smart oxide reported by the Department of Science and Technology: 1. The material can store energy and also change colour to show the amount of charge. 2. The report says most electronic devices commonly store energy and display information at the same time. 3. In a device made with this oxide, the colour changes from blue in the charged state to transparent in the discharged state. Which of the statements given above are correct?
Statements 1 and 3 are correct. DST describes a material that stores energy, changes colour to indicate charge, and changes from blue when charged to transparent when discharged. Statement 2 is incorrect because DST says most devices rarely do both storage and display.
Q3Consider the following statements about large-area chromogenic and electrochromic switching: 1. Such devices can be used for dynamic control of light through building and vehicle glazings. 2. Chromogenic glazings can be used to modulate reflector surfaces for automotive mirrors. 3. In the visible region, switching ranges can go from as high as 80% to 5-10% transmittance. 4. Long-term memory in these devices cannot be maintained without a holding potential. Which of the statements given above are correct?
Statements 1, 2 and 3 are correct. Berkeley Lab's publication abstract identifies dynamic control through building and vehicle glazings, modulation of reflector surfaces for automotive mirrors, and visible-region switching from 80% to 5-10% transmittance. Statement 4 is incorrect because the same abstract says long-term memory can be maintained for several hours without a holding potential.
Q4Consider the following statements about the DST-supported transparent battery prototype: 1. The aqueous electrolyte in the prototype was described as having two orders of magnitude higher ion conductivity than a gel electrolyte. 2. The device showed an areal discharge capacity of 155 milliampere-hour per square metre and an optical contrast of 68 percent. 3. The DST release says a single cathode improves the device's specific capacity and optical contrast compared with a dual-cathode design. 4. The project was supported by the Council of Scientific and Industrial Research, according to the DST release. Which of the statements given above are correct?
Statements 1 and 2 are correct: the prototype used an aqueous electrolyte with much higher ion conductivity than gel electrolyte and reported 155 milliampere-hour per square metre capacity with 68 percent optical contrast. Statement 3 is false because the cited improvement came from two transparent cathodes. Statement 4 is false because the support named in the release is from the Technology Development Board of DST.
Q5Consider the following statements about transmission and reflectance modes of electrochromic devices: 1. In transmission mode, transparent conducting electrodes control light intensity passing through them. 2. Transmission mode is used in smart-window applications. 3. Reflectance mode is described as useful only in solar cells, not in rear-view mirrors or display devices. Which of the statements given above are correct?
Statements 1 and 2 are true: transmission mode uses transparent conducting electrodes and is used in smart windows. Statement 3 is false because reflectance mode is also used in car rear-view mirrors and electrochromic display devices.
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6Consider the following statements about specific electrochromic material classes: 1. PEDOT can be deep blue in the neutral state and transparent sky-blue in the oxidised state. 2. Organic molecules may face durability limits in applications because of sensitivity to ultraviolet radiation. 3. A ruthenium complex cited in an electrochromic-supercapacitor review is orange in the Ru3+ state and transparent in the Ru2+ state. 4. Viologens display colour because of oxidation from their neutral form, not because of reduction. Which of the statements given above are correct?
7Consider the following statements about grid lines in a DOE dynamic-window project: 1. Grid lines on the optically active working electrode were to decrease sheet resistance of the transparent conducting oxide. 2. Counter-electrode grid lines were to provide a uniform source of metal ions across the device area. 3. The project aimed to avoid grid lines because they necessarily prevent any metal-ion supply. Which of the statements given above are correct?
8Consider the following statements about electrochromic glazings: 1. Berkeley Lab describes electrochromic glazings as capable of dynamically controlling light transmission. 2. Electrochromic glazings are classified outside chromogenic light-control technologies. 3. A cited visible-light transmission range for an LBL electrochromic window is 0.68 to 0.10. 4. These glazings are useful only in aircraft and not in buildings or automobiles. Which of the statements given above are correct?
9Consider the following statements about NREL's description of electrochromic smart windows: 1. Electrochromic phenomena involve reversible changes in optical properties induced by an externally applied electric field or current. 2. Tungsten oxide is described as a preferred material for electrochromic devices because of superior optical and electrical properties. 3. A typical electrochromic device is placed between two opaque metallic plates; transparent conducting oxides are not part of the device stack. 4. In its unactivated state, the described electrochromic device is optically clear and transmits about 70% to 80% of incident light. Which of the statements given above are correct?
10Consider the following statements about applications of large-area chromogenic devices: 1. They can be used for dynamic control of light through building and vehicle glazings. 2. They can be used for certain information-display applications. 3. They can be used for modulation of reflector surfaces for automotive mirrors. Which of the statements given above are correct?
11Consider the following statements about electrochromic devices: 1. An electrochromic device controls optical properties such as transmission or reflectance reversibly when voltage is applied. 2. Electrochromic smart windows are mainly designed to increase sunlight entry without controlling it. 3. Electrochromic glazings typically require power only to change transmission, not to hold a memorised state. 4. Electrochromic devices are unrelated to displays and mirrors. Which of the statements given above are correct?
12Consider the following statements about dynamic windows: 1. Most dynamic windows use electrochromic materials that change transmission when a voltage is applied. 2. Such windows can modulate transparency toward visible and/or infrared light. 3. In dynamic windows, electrochromic materials change transparency without any voltage-related stimulus. Which of the statements given above are correct?
13Consider the following statements about a smart oxide reported by the Department of Science and Technology: 1. It was developed at the Nano and Soft Matter Sciences, Bengaluru. 2. It is an oxygen-deficient bimetallic oxide based on sodium and nickel. 3. In a device made with this oxide, the colour changes from blue in the charged state to transparent in the discharged state. Which of the statements given above are correct?
14Consider the following statements about electrochromic device structure: 1. A typical electrochromic device can contain counter electrode, ion storage, ion transport, electrochromic and working-electrode layers. 2. Transparent conductive oxides such as indium tin oxide and fluorine-doped tin dioxide are used as electrode materials. 3. The ion-transport layer is meant to block all ionic movement between electrodes. Which of the statements given above are correct?
15Consider the following statements about electrochromic devices: 1. Electrochromism involves a reversible change in the optical absorption of a material under an applied voltage. 2. Electrochromic materials are used in smart windows and car rear-view mirrors. 3. Their optical change is caused only by thermal expansion, not by any oxidation-state change. Which of the statements given above are correct?